KVO

来源：互联网发布：郑州软件定制编辑：程序博客网时间：2024/06/11 00:51

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ViewController.m#import "ViewController.h"#import "Student.h"#import "SecondViewController.h"@interface ViewController ()@property(nonatomic, retain)Student *stu;@property(nonatomic, retain)UITextField *textField;@end@implementation ViewController- (void)viewDidLoad {    //  KVC  Key - Value - Coding    //  KVO  Key - Value - Observer 键值观察者.监控属性的值得变化,只要变化就会触发相应的操作.    self.stu = [[Student alloc] init];    // 注册一个观察者    // 参数1:给对象添加一个观察者,就是当前类的对象self.    // 参数2:需要监控的属性名.    // 参数3:触发的条件,旧内容变成新内容就会触发.    [self.stu addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew context:@"监控的文本"];    self.stu.name = @"韩老师";

用此方法来监控目标对象.- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {    NSLog(@"%@", change[@"new"]);    NSLog(@"%@", keyPath);}

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1.传值的第四种方式:通知中心也叫消息中心.    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(100, 100, 100, 50);    button.backgroundColor = [UIColor yellowColor];    [button setTitle:@"前往" forState:UIControlStateNormal];    [button addTarget:self action:@selector(goClick:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];    // 给通知中心加上一个观察者.    // 参数1:添加一个观察者.    // 参数2:需要绑定一个方法.    // 参数3:给name起一个名.    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(backValue:) name:@"test" object:nil];

按钮绑定的方法.- (void)goClick:(UIButton *)button {    SecondViewController *secondVC  = [[SecondViewController alloc] init];    [secondVC setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];    [self presentViewController:secondVC animated:YES completion:^{    }];    [secondVC release];}打印通知中心传回来的字典.- (void)backValue:(NSNotification *)notification {    NSLog(@"%@", notification.userInfo);}

SecondViewController.m- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    self.view.backgroundColor = [UIColor cyanColor];    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(100, 100, 100, 50);    button.backgroundColor = [UIColor greenColor];    [button setTitle:@"返回" forState:UIControlStateNormal];    [button addTarget:self action:@selector(backClick:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];}- (void)backClick:(UIButton *)button {    // 把值进行返回.    [[NSNotificationCenter defaultCenter] postNotificationName:@"test" object:nil userInfo:@{@"1":@"2"}];    [self dismissViewControllerAnimated:YES completion:^{    }];}

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self.textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 200, 150, 50)];    self.textField.backgroundColor = [UIColor greenColor];    [self.view addSubview:self.textField];    [_textField release];    self.textField.layer.borderWidth = 1;    self.textField.layer.cornerRadius = 10;2.第一种:监听textField输入内容的方法.    [self.textField addTarget:self action:@selector(changeValue:) forControlEvents:UIControlEventEditingChanged];

监控文本框的输入内容,正在编辑.- (void)changeValue:(UITextField *)textField {    NSLog(@"%@", textField.text);}

3.第二种:通过通知中心监听textField的内容,编辑完成.//     参数3:在textField头文件的最后几行//     参数4:要监听的对象    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(value:) name:UITextFieldTextDidChangeNotification object:self.textField];

编辑完成的方法,用正则表达式和谓词.- (void)value:(NSNotification *)natification {    NSLog(@"%@", self.textField.text);    // 这个正则表达式是用来判断一个内容格式是否相符的字符串,正则表达式有自己的语法规则,需要的话,百度.    NSString *str = @"^((13[0-9])|(147)|(15[^4,\\D])|(18[0,5-9]))\\d{8}$";    // 通过谓词来进行内容的比对.    NSPredicate *cate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", str];    if ([cate evaluateWithObject:self.textField.text]) {        NSLog(@"YES");    } else {        NSLog(@"NO");    }}

- (void)dealloc{    // ARC下可以写dealloc方法,但是不能写[super dealloc],它需要把观察者从对象上移除掉    [self.stu removeObserver:self forKeyPath:@"name"];    [_stu release];    [super dealloc];}

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