IOS 同步异步请求JSON数据

IOS SDK为HTTP请求提供了同步和异步两种请求这种不同的API,而且可以使用Get或POST等请求方法。

1.同步Get请求

在贴代码之前先对项目有个整体的说明：如图所示

首先新建Master-Detail Application类型项目，我们可以看到会自动帮我们新建一些类，然后通过手动添加NSString_URLEncoding.h和NSNumber+Message.h类库主要用于对URL编码和对消息进行处理。
在MasterViewController类里添加如下变量以及方法
类接口

#import <UIKit/UIKit.h>@class DetailViewController;@interface MasterViewController : UITableViewController@property (strong, nonatomic) DetailViewController *detailViewController;@property(strong,nonatomic)NSMutableArray *listData;-(void)reloadView:(NSDictionary *)res;-(void)startRequest;@end

类实现

#import "MasterViewController.h"#import "DetailViewController.h"#import "NotesXMLParser.h"#import "NSString+URLEncoding.h"#import "NSNumber+Message.h"#import "NotesTBXMLParser.h"@interface MasterViewController ()@property NSMutableArray *objects;@end@implementation MasterViewController@synthesize listData;- (void)viewDidLoad {    [super viewDidLoad];    self.navigationItem.leftBarButtonItem = self.editButtonItem;    UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject:)];    self.navigationItem.leftBarButtonItem=self.editButtonItem;//    self.navigationItem.rightBarButtonItem = addButton;//    self.detailViewController = (DetailViewController *)[[self.splitViewController.viewControllers lastObject] topViewController];    self.detailViewController=(DetailViewController *)[[self.splitViewController.viewControllers lastObject]topViewController];    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(reloadView:) name:@"reloadViewNotification" object:nil];//    NotesXMLParser *parser=[NotesXMLParser new];//    [parser start];//    NSString *path=[[NSBundle mainBundle]pathForResource:@"Notes" ofType:@"json"];//    NSData *jsonData=[[NSData alloc]initWithContentsOfFile:path];//    //    NSError *error;//    id jsonObj=[NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableLeaves error:&error];//    //    if(!jsonObj||error)//    {//        NSLog(@"JSON解码失败");//    }//    self.listData=[jsonObj objectForKey:@"Record"];    [self startRequest];//    NotesTBXMLParser *parser=[NotesTBXMLParser new];//    [parser start];}-(void)reloadView:(NSDictionary *)res{    NSNumber *resultCodeObj=[res objectForKey:@"ResultCode"];    if([resultCodeObj integerValue]>=0)    {        self.listData=[res objectForKey:@"Record"];        [self.tableView reloadData];    }else    {        NSString *errorStr=[resultCodeObj errorMessage];        UIAlertView *alterView=[[UIAlertView alloc]initWithTitle:@"错误信息" message:errorStr delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];        [alterView show];    }}-(void)startRequest{    NSString *strURL=[[NSString alloc]initWithFormat:@"http://www.51work6.com/service/mynotes/WebService.php?email=%@&type=%@&action=%@",@"[e-mail]",@"JSON",@"query"];//    NSURL *url=[strURL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];    NSURL *url=[NSURL URLWithString:[strURL URLEncodedString]];    NSURLRequest *request=[[NSURLRequest alloc]initWithURL:url];    NSDate *data=[NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];    NSLog(@"请求完成…");    NSDictionary *resDict=[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];    [self reloadView:resDict];}//-(void)reloadView:(NSNotification *)notification//{//    NSMutableArray *resList=[notification object];//    self.listData=resList;//    [self.tableView reloadData];//}- (void)viewWillAppear:(BOOL)animated {    self.clearsSelectionOnViewWillAppear = self.splitViewController.isCollapsed;    [super viewWillAppear:animated];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}- (void)insertNewObject:(id)sender {    if (!self.objects) {        self.objects = [[NSMutableArray alloc] init];    }    [self.objects insertObject:[NSDate date] atIndex:0];    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];    [self.tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];}#pragma mark - Segues- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {    if ([[segue identifier] isEqualToString:@"showDetail"]) {        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];        NSDate *object = self.objects[indexPath.row];        DetailViewController *controller = (DetailViewController *)[[segue destinationViewController] topViewController];        [controller setDetailItem:object];        controller.navigationItem.leftBarButtonItem = self.splitViewController.displayModeButtonItem;        controller.navigationItem.leftItemsSupplementBackButton = YES;    }}#pragma mark - Table View- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {    return 1;}- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {    return self.listData.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];    NSMutableDictionary *dict=self.listData[indexPath.row];    //NSDate *object = self.objects[indexPath.row];    cell.textLabel.text = [dict objectForKey:@"Content"];    cell.detailTextLabel.text=[dict objectForKey:@"CDate"];    return cell;}- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {    // Return NO if you do not want the specified item to be editable.    return YES;}- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {    if (editingStyle == UITableViewCellEditingStyleDelete) {        [self.objects removeObjectAtIndex:indexPath.row];        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];    } else if (editingStyle == UITableViewCellEditingStyleInsert) {        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.    }}@end

其中startRequest是请求Webservice服务器连接服务的方法

-(void)startRequest{    NSString *strURL=[[NSString alloc]initWithFormat:@"http://www.51work6.com/service/mynotes/WebService.php?email=%@&type=%@&action=%@",@"[e-mail]",@"JSON",@"query"];//    NSURL *url=[strURL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];    NSURL *url=[NSURL URLWithString:[strURL URLEncodedString]];    NSURLRequest *request=[[NSURLRequest alloc]initWithURL:url];    NSDate *data=[NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];    NSLog(@"请求完成…");    NSDictionary *resDict=[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];    [self reloadView:resDict];}

通过NSJSONSerialization类解析返回的数据，并将数据给tableView.
结果如图所示：

通过浏览器返回的JSON对象是这样的：

{"ResultCode":0,"Record":[{"ID":4290,"CDate":"2016-05-18","Content":"欢迎来到智捷课堂。"}]}

2.异步Get请求
还有一点需要说明的是：

Google后查证，iOS9引入了新特性App Transport Security (ATS)。详情：App Transport Security (ATS)新特性要求App内访问的网络必须使用HTTPS协议。但是现在公司的项目使用的是HTTP协议，使用私有加密方式保证数据安全。现在也不能马上改成HTTPS协议传输。

需要在Info.plist里添加如下选项，如图所示：

同步请求的用户体验不是很好，因此很多情况我们会采用异步调用。iOS SDK也提供了异步请求的方法，而异步请求会使用NSURLConnection委托协议NSURLConnectionDataDelegate.在请求的不同阶段会回调委托对象的不同方法。NSURLConnectionDataDelegate协议如下：

/*        NSURLConnection.h    Copyright (c) 2003-2015, Apple Inc. All rights reserved.        Public header file.*/#import <Foundation/NSObject.h>@class NSArray;@class NSURL;@class NSCachedURLResponse;@class NSData;@class NSError;@class NSURLAuthenticationChallenge;@class NSURLConnectionInternal;@class NSURLRequest;@class NSURLResponse;@class NSRunLoop;@class NSInputStream;@class NSURLProtectionSpace;@class NSOperationQueue;@protocol NSURLConnectionDelegate;NS_ASSUME_NONNULL_BEGIN/*** DEPRECATED: The NSURLConnection class should no longer be used.  NSURLSession is the replacement for NSURLConnection ***//*!    @class NSURLConnection    @abstract         An NSURLConnection object provides support to perform        asynchronous loads of a URL request, providing data to a        client supplied delegate.    @discussion        The interface for NSURLConnection is very sparse, providing        only the controls to start and cancel asynchronous loads of a        URL request.<p>        An NSURLConnection may be used for loading of resource data        directly to memory, in which case an        NSURLConnectionDataDelegate should be supplied, or for        downloading of resource data directly to a file, in which case        an NSURLConnectionDownloadDelegate is used.  The delegate is        retained by the NSURLConnection until a terminal condition is        encountered.  These two delegates are logically subclasses of        the base protocol, NSURLConnectionDelegate.<p>        A terminal condition produced by the loader will result in a        connection:didFailWithError: in the case of an error, or        connectiondidFinishLoading: or connectionDidFinishDownloading:        delegate message.<p>        The -cancel message hints to the loader that a resource load        should be abandoned but does not guarantee that more delegate        messages will not be delivered.  If -cancel does cause the        load to be abandoned, the delegate will be released without        further messages.  In general, a caller should be prepared for        -cancel to have no effect, and internally ignore any delegate        callbacks until the delegate is released.        Scheduling of an NSURLConnection specifies the context in        which delegate callbacks will be made, but the actual IO may        occur on a separate thread and should be considered an        implementation detail.<p>        When created, an NSURLConnection performs a deep-copy of the        NSURLRequest.  This copy is available through the        -originalRequest method.  As the connection performs the load,        this request may change as a result of protocol        canonicalization or due to following redirects.        -currentRequest can be used to retrieve this value.<p>        An NSURLConnections created with the        +connectionWithRequest:delegate: or -initWithRequest:delegate:        methods are scheduled on the current runloop immediately, and        it is not necessary to send the -start message to begin the        resource load.<p>        NSURLConnections created with        -initWithRequest:delegate:startImmediately: are not        automatically scheduled.  Use -scheduleWithRunLoop:forMode: or        -setDelegateQueue: to specify the context for delegate        callbacks, and -start to begin the load.  If you do not        explicitly schedule the connection before -start, it will be        scheduled on the current runloop and mode automatically.<p>        The NSURLConnectionSynchronousLoading category adds        +sendSynchronousRequest:returningResponse:error, which blocks        the current thread until the resource data is available or an        error occurs.  It should be noted that using this method on an        applications main run loop may result in an unacceptably long        delay in a user interface and its use is strongly        discourage.<p>        The NSURLConnectionQueuedLoading category implements        +sendAsynchronousRequest:queue:completionHandler, providing        similar simplicity but provides a mechanism where the current        runloop is not blocked.<p>        Both of the immediate loading categories do not provide for        customization of resource load, and do not allow the caller to        respond to, e.g., authentication challenges.<p>*/@interface NSURLConnection : NSObject{    @private    NSURLConnectionInternal *_internal;}/* Designated initializer */- (nullable instancetype)initWithRequest:(NSURLRequest *)request delegate:(nullable id)delegate startImmediately:(BOOL)startImmediately NS_DEPRECATED(10_5, 10_11, 2_0, 9_0, "Use NSURLSession (see NSURLSession.h)") __WATCHOS_PROHIBITED;- (nullable instancetype)initWithRequest:(NSURLRequest *)request delegate:(nullable id)delegate NS_DEPRECATED(10_3, 10_11, 2_0, 9_0, "Use NSURLSession (see NSURLSession.h)") __WATCHOS_PROHIBITED;+ (nullable NSURLConnection*)connectionWithRequest:(NSURLRequest *)request delegate:(nullable id)delegate NS_DEPRECATED(10_3, 10_11, 2_0, 9_0, "Use NSURLSession (see NSURLSession.h)") __WATCHOS_PROHIBITED;@property (readonly, copy) NSURLRequest *originalRequest NS_AVAILABLE(10_8, 5_0);@property (readonly, copy) NSURLRequest *currentRequest NS_AVAILABLE(10_8, 5_0);- (void)start NS_AVAILABLE(10_5, 2_0);- (void)cancel;- (void)scheduleInRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode NS_AVAILABLE(10_5, 2_0);- (void)unscheduleFromRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode NS_AVAILABLE(10_5, 2_0);- (void)setDelegateQueue:(nullable NSOperationQueue*) queue NS_AVAILABLE(10_7, 5_0);/*!     @method         canHandleRequest:    @abstract                    Performs a "preflight" operation that performs                    some speculative checks to see if a connection can                    be initialized, and the associated I/O that is                    started in the initializer methods can begin.    @discussion                    The result of this method is valid only as long as                    no protocols are registered or unregistered, and                    as long as the request is not mutated (if the                    request is mutable). Hence, clients should be                    prepared to handle failures even if they have                    performed request preflighting by calling this                    method.    @param         request     The request to preflight.    @result        YES         if it is likely that the given request can be used to                    initialize a connection and the associated I/O can be                    started        NO            */+ (BOOL)canHandleRequest:(NSURLRequest *)request;@end/*!    @protocol       NSURLConnectionDelegate    @abstract                            Delegate methods that are common to all forms of                    NSURLConnection.  These are all optional.  This                    protocol should be considered a base class for the                    NSURLConnectionDataDelegate and                    NSURLConnectionDownloadDelegate protocols.    @discussion                    connection:didFailWithError: will be called at                    most once, if an error occurs during a resource                    load.  No other callbacks will be made after.<p>                    connectionShouldUseCredentialStorage: will be                    called at most once, before a resource load begins                    (which means it may be called during construction                    of the connection.)  The delegate should return                    TRUE if the connection should consult the shared                    NSURLCredentialStorage in response to                    authentication challenges.  Regardless of the                    result, the authentication challenge methods may                    still be called.                    connection:willSendRequestForAuthenticationChallenge:                    is the preferred (Mac OS X 10.7 and iOS 5.0 or                    later) mechanism for responding to authentication                    challenges.  See                    <Foundation/NSURLAuthenticationChallenge.h> for                    more information on dealing with the various types                    of authentication challenges.                    connection:canAuthenticateAgainstProtectionSpace:                    connection:didReciveAuthenticationChallenge:                    connection:didCancelAuthenticationChallenge: are                    deprected and new code should adopt                    connection:willSendRequestForAuthenticationChallenge.                    The older delegates will still be called for                    compatability, but incur more latency in dealing                    with the authentication challenge.*/@protocol NSURLConnectionDelegate <NSObject>@optional- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error;- (BOOL)connectionShouldUseCredentialStorage:(NSURLConnection *)connection;- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge;- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace NS_DEPRECATED(10_6, 10_10, 3_0, 8_0, "Use -connection:willSendRequestForAuthenticationChallenge: instead.");- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge NS_DEPRECATED(10_2, 10_10, 2_0, 8_0, "Use -connection:willSendRequestForAuthenticationChallenge: instead.");- (void)connection:(NSURLConnection *)connection didCancelAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge NS_DEPRECATED(10_2, 10_10, 2_0, 8_0, "Use -connection:willSendRequestForAuthenticationChallenge: instead.");@end/*!    @protocol       NSURLConnectionDataDelegate    @abstract                            Delegate methods used for loading data to memory.                    These delegate methods are all optional.    @discussion                    connection:willSendRequest:redirectResponse: is                    called whenever an connection determines that it                    must change URLs in order to continue loading a                    request.  This gives the delegate an opportunity                    inspect and if necessary modify a request.  A                    delegate can cause the request to abort by either                    calling the connections -cancel method, or by                    returning nil from this callback.<p>                    There is one subtle difference which results from                    this choice. If -cancel is called in the delegate                    method, all processing for the connection stops,                    and no further delegate callbacks will be sent. If                    the delegate returns nil, the connection will                    continue to process, and this has special                    relevance in the case where the redirectResponse                    argument is non-nil. In this case, any data that                    is loaded for the connection will be sent to the                    delegate, and the delegate will receive a finished                    or failure delegate callback as appropriate.<p>                    connection:didReceiveResponse: is called when                    enough data has been read to construct an                    NSURLResponse object. In the event of a protocol                    which may return multiple responses (such as HTTP                    multipart/x-mixed-replace) the delegate should be                    prepared to inspect the new response and make                    itself ready for data callbacks as appropriate.<p>                    connection:didReceiveData: is called with a single                    immutable NSData object to the delegate,                    representing the next portion of the data loaded                    from the connection.  This is the only guaranteed                    for the delegate to receive the data from the                    resource load.<p>                    connection:needNewBodyStream: is called when the                    loader must retransmit a requests payload, due to                    connection errors or authentication challenges.                    Delegates should construct a new unopened and                    autoreleased NSInputStream.  If not implemented,                    the loader will be required to spool the bytes to                    be uploaded to disk, a potentially expensive                    operation.  Returning nil will cancel the                    connection.                    connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:                    is called during an upload operation to provide                    progress feedback.  Note that the values may                    change in unexpected ways if the request needs to                    be retransmitted.<p>                    connection:willCacheResponse: gives the delegate                    an opportunity to inspect and modify the                    NSCachedURLResponse which will be cached by the                    loader if caching is enabled for the original                    NSURLRequest.  Returning nil from this delegate                    will prevent the resource from being cached.  Note                    that the -data method of the cached response may                    return an autoreleased in-memory copy of the true                    data, and should not be used as an alternative to                    receiving and accumulating the data through                    connection:didReceiveData:<p>                    connectionDidFinishLoading: is called when all                    connection processing has completed successfully,                    before the delegate is released by the                    connection.<p>*/@protocol NSURLConnectionDataDelegate <NSURLConnectionDelegate>@optional- (nullable NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(nullable NSURLResponse *)response;- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response;- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data;- (nullable NSInputStream *)connection:(NSURLConnection *)connection needNewBodyStream:(NSURLRequest *)request;- (void)connection:(NSURLConnection *)connection   didSendBodyData:(NSInteger)bytesWritten                                                 totalBytesWritten:(NSInteger)totalBytesWritten                                         totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite;- (nullable NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse;- (void)connectionDidFinishLoading:(NSURLConnection *)connection;@end/*!    @protocol       NSURLConnectionDownloadDelegate    @abstract                    Delegate methods used to perform resource                    downloads directly to a disk file.  All the                    methods are optional with the exception of                    connectionDidFinishDownloading:destinationURL:                    which must be implemented in order to inform the                    delegate of the location of the finished download.                    This delegate and download implementation is                    currently only available on iOS 5.0 or later.    @discussion                    connection:didWriteData:totalBytesWritten:expectedTotalBytes:                    provides progress information about the state of                    the download, the number of bytes written since                    the last delegate callback, the total number of                    bytes written to disk and the total number of                    bytes that are expected (or 0 if this is unknown.)                    connectionDidResumeDownloading:totalBytesWritten:expectedTotalBytes:                    is called when the connection is able to resume an                    in progress download.  This may happen due to a                    connection or network failure.                    connectionDidFinishDownloading:destinationURL: is                    a terminal event which indicates the completion of                    a download and provides the location of the file.                    The file will be located in the applications cache                    directory and is guaranteed to exist for the                    duration of the delegate callback.  The                    implication is that the delegate should copy or                    move the download to a more persistent location if                    desired.*/@protocol NSURLConnectionDownloadDelegate <NSURLConnectionDelegate>@optional- (void)connection:(NSURLConnection *)connection didWriteData:(long long)bytesWritten totalBytesWritten:(long long)totalBytesWritten expectedTotalBytes:(long long) expectedTotalBytes;- (void)connectionDidResumeDownloading:(NSURLConnection *)connection totalBytesWritten:(long long)totalBytesWritten expectedTotalBytes:(long long) expectedTotalBytes;@required- (void)connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *) destinationURL;@end/*!    @category    NSURLConnection(NSURLConnectionSynchronousLoading)    @abstract                 The NSURLConnectionSynchronousLoading category on                 NSURLConnection provides the interface to perform                 synchronous loading of URL requests.*/@interface NSURLConnection (NSURLConnectionSynchronousLoading)/*!     @method      sendSynchronousRequest:returningResponse:error:    @abstract                  Performs a synchronous load of the given request,                 returning an NSURLResponse in the given out                 parameter.    @discussion                 A synchronous load for the given request is built on                 top of the asynchronous loading code made available                 by the class.  The calling thread is blocked while                 the asynchronous loading system performs the URL load                 on a thread spawned specifically for this load                 request. No special threading or run loop                 configuration is necessary in the calling thread in                 order to perform a synchronous load. For instance,                 the calling thread need not be running its run loop.    @param       request   The request to load. Note that the request is                 deep-copied as part of the initialization                 process. Changes made to the request argument after                 this method returns do not affect the request that is                 used for the loading process.    @param       response  An out parameter which is filled in with the                 response generated by performing the load.    @param       error     Out parameter (may be NULL) used if an error occurs                 while processing the request. Will not be modified if the                  load succeeds.    @result      The content of the URL resulting from performing the load,                 or nil if the load failed.*/+ (nullable NSData *)sendSynchronousRequest:(NSURLRequest *)request returningResponse:(NSURLResponse * __nullable * __nullable)response error:(NSError **)error NS_DEPRECATED(10_3, 10_11, 2_0, 9_0, "Use [NSURLSession dataTaskWithRequest:completionHandler:] (see NSURLSession.h") __WATCHOS_PROHIBITED;@end/*!    @category NSURLConnection(NSURLConnectionQueuedLoading)    The NSURLConnectionQueuedLoading category on NSURLConnection    provides the interface to perform asynchronous loading of URL    requests where the results of the request are delivered to a    block via an NSOperationQueue.    Note that there is no guarantee of load ordering implied by this    method. */@interface NSURLConnection (NSURLConnectionQueuedLoading)/*!    @method       sendAsynchronousRequest:queue:completionHandler:    @abstract                   Performs an asynchronous load of the given                  request. When the request has completed or failed,                  the block will be executed from the context of the                  specified NSOperationQueue.    @discussion                  This is a convenience routine that allows for                  asynchronous loading of an url based resource.  If                  the resource load is successful, the data parameter                  to the callback will contain the resource data and                  the error parameter will be nil.  If the resource                  load fails, the data parameter will be nil and the                  error will contain information about the failure.    @param         request   The request to load. Note that the request is                   deep-copied as part of the initialization                   process. Changes made to the request argument after                   this method returns do not affect the request that                   is used for the loading process.    @param          queue     An NSOperationQueue upon which    the handler block will                   be dispatched.    @param         handler   A block which receives the results of the resource load. */+ (void)sendAsynchronousRequest:(NSURLRequest*) request                          queue:(NSOperationQueue*) queue              completionHandler:(void (^)(NSURLResponse* __nullable response, NSData* __nullable data, NSError* __nullable connectionError)) handler NS_DEPRECATED(10_7, 10_11, 5_0, 9_0, "Use [NSURLSession dataTaskWithRequest:completionHandler:] (see NSURLSession.h") __WATCHOS_PROHIBITED;@endNS_ASSUME_NONNULL_END

需要实现的主要方法有如下几个：
connection:didReceiveData
connection:didFailWithError:
connectionDidFinishLoading:
具体使用代码中会介绍。
MasterViewController接口：

#import <UIKit/UIKit.h>@class DetailViewController;@interface MasterViewController : UITableViewController@property (strong, nonatomic) DetailViewController *detailViewController;@property(nonatomic,strong)NSMutableArray *objects;@property(nonatomic,strong)NSMutableData *datas;-(void)reloadView:(NSDictionary *)res;-(void)startRequest;;@end

MasterViewController实现：

#import "MasterViewController.h"#import "DetailViewController.h"#import "NSNumber+Message.h"@interface MasterViewController ()<NSURLConnectionDataDelegate>@end@implementation MasterViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    self.navigationItem.leftBarButtonItem = self.editButtonItem;    UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject:)];    self.navigationItem.rightBarButtonItem = addButton;    self.detailViewController = (DetailViewController *)[[self.splitViewController.viewControllers lastObject] topViewController];    [self startRequest];}-(void)startRequest{    NSString *strURL=[[NSString alloc]initWithFormat:@"http://www.51work6.com/service/mynotes/WebService.php?email=%@&type=%@&action=%@",@"[e-mail]",@"JSON",@"query"];    strURL=[strURL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];    NSURL *url=[NSURL URLWithString:strURL];    NSURLRequest *request=[[NSURLRequest alloc]initWithURL:url];    NSURLConnection *connection=[[NSURLConnection alloc]initWithRequest:request delegate:self];    if(connection)    {        self.datas=[NSMutableData new];    }}- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{    [self.datas appendData:data];}- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{    NSLog(@"%@",[error localizedDescription]);}- (void)connectionDidFinishLoading:(NSURLConnection *)connection{    NSDictionary *dict=[NSJSONSerialization JSONObjectWithData:self.datas options:NSJSONReadingMutableLeaves error:nil];    [self reloadView:dict];}-(void)reloadView:(NSDictionary *)res{    NSNumber *resultCode=[res objectForKey:@"ResultCode"];    if([resultCode integerValue]>=0)    {        self.objects=[res objectForKey:@"Record"];        [self.tableView reloadData];    }else    {        NSString *errorStr=[resultCode errorMessage];        UIAlertView *alertView=[[UIAlertView alloc]initWithTitle:@"错误信息" message:errorStr delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];        [alertView show];    }}- (void)viewWillAppear:(BOOL)animated {    self.clearsSelectionOnViewWillAppear = self.splitViewController.isCollapsed;    [super viewWillAppear:animated];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}- (void)insertNewObject:(id)sender {    if (!self.objects) {        self.objects = [[NSMutableArray alloc] init];    }    [self.objects insertObject:[NSDate date] atIndex:0];    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];    [self.tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];}#pragma mark - Segues- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {    if ([[segue identifier] isEqualToString:@"showDetail"]) {        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];        NSDate *object = self.objects[indexPath.row];        DetailViewController *controller = (DetailViewController *)[[segue destinationViewController] topViewController];        [controller setDetailItem:object];        controller.navigationItem.leftBarButtonItem = self.splitViewController.displayModeButtonItem;        controller.navigationItem.leftItemsSupplementBackButton = YES;    }}#pragma mark - Table View- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {    return 1;}- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {    return self.objects.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];    NSMutableDictionary *dict=self.objects[indexPath.row];    cell.textLabel.text = [dict objectForKey:@"Content"];    cell.detailTextLabel.text=[dict objectForKey:@"CDate"];    return cell;}- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {    // Return NO if you do not want the specified item to be editable.    return YES;}- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {    if (editingStyle == UITableViewCellEditingStyleDelete) {        [self.objects removeObjectAtIndex:indexPath.row];        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];    } else if (editingStyle == UITableViewCellEditingStyleInsert) {        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.    }}@end

调用结果和之前一样。至此所有的功能描述都已经结束，希望能给大家帮助！