2011斯坦福大学iOS应用开发教程学习笔记(第五课)Protocols,手势识别

第五课内容： 自动旋转、 Protocols、 手势识别、一个自定义UIView的Demo

1、自动旋转

当设备旋转时，你的controller会做什么呢？你可以控制界面是否和设备一起一起旋转。

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)orientation{return UIInterfaceOrientationIsPortrait(orientation); // only support portrait return YES; // support all orientationsreturn (orientation != UIInterfaceOrientationPortraitUpsideDown); // anything but}

当旋转的时候，view的bounds会改变，子view的frame,子view的子view也会改变。

改变的规则是：struts和springs。

当view的bound改变时，drawRect不会默认调用

红色的I就是struts，中间的红色箭头就是springs。

右边红白色的显示屏似的就是用动画告诉你view如何改变。白色的是父view，红色的是你选中的view。

这个控制在iPhone上一般使用不到，因为屏幕太小了。

幸运的是，有UIView有这么个属性来控制

三种控制方式：

1、

@property (nonatomic) UIViewContentMode contentMode;

UIViewContentMode{Left,Right,Top,Right,BottomLeft,BottomRight,TopLeft,TopRight}

2、缩放的控制属性：

UIViewContentModeScale{ToFill,AspectFill,AspectFit} // bit stretching/shrinking

分别是填充，内容填充，内容适应。 toFill是默认的模式，它会自动缩放像素点填满新的空间，可能会造成图形扭曲。

3、

@property (nonatomic) CGRect contentStretch;

指定某一个区域拉伸

初始化一个UIView.

2、协议procotol

@protocol Foo <Other, NSObject> // implementors must implement Other and NSObject too- (void)doSomething; // implementors must implement this (methods are @required by default) @optional- (int)getSomething; // implementors do not have to implement this- (void)doSomethingOptionalWithArgument:(NSString *)argument; // also optional@required- (NSArray *)getManySomethings:(int)howMany; // back to being “must implement” @property (nonatomic, strong) NSString *fooProp; // note that you must specify strength@end

可以定义在自己的头文件里，也可以定义在其他类的头文件中。

实现协议，并使用的语法：

#import “Foo.h” // importing the header file that declares the Foo @protocol @interface MyClass : NSObject <Foo> // MyClass is saying it implements the Foo @protocol...@en

id <Foo> obj = [[MyClass alloc] init];

@property (nonatomic, weak) id <Foo> myFooProperty; // properties too!

协议的主要作用：

实现委托和数据源。
委托几乎都是weak的，因为被设置为委托的对象通常都是委托对象的所有者或创建者。

比如controller通常把自己设置成view的委托或数据源，你不要它们相互的strong指针指向。

scrollView例子

@protocol UIScrollViewDelegate@optional- (UIView *)viewForZoomingInScrollView:(UIScrollView *)sender;- (void)scrollViewDidEndDragging:(UIScrollView *)sender willDecelerate:(BOOL)decelerate;@end@interface UIScrollView : UIView@property (nonatomic, weak) id <UIScrollViewDelegate> delegate;@end@interface MyViewController : UIViewController <UIScrollViewDelegate>@property (nonatomic, weak) IBOutlet UIScrollView *scrollView;@end@implementation MyViewController- (void)setScrollView:(UIScrollView *)scrollView {    _scrollView = scrollView;self.scrollView.delegate = self; // compiler won’t complain }- (UIView *)viewForZoomingInScrollView:(UIScrollView *)sender { return ... }; @end

3、手势识别

如何获得触摸事件呢？

得到触摸时间的通知

相应预定义好的手势

UIGestureRecognizer类，它是个抽象类，需要实现。

使用手势识别有两步骤:

先创建一个手势，把它附到UIView上，然后当手势被识别时进行处理。

第一步由controller来完成

第二步由UIView自己完成

从controller添加一个手势到UIView：

- (void)setPannableView:(UIView *)pannableView      {          _pannableView = pannableView;          UIPanGestureRecognizer *pangr =              [[UIPanGestureRecognizer alloc] initWithTarget:pannableView action:@selector(pan:)];          [pannableView addGestureRecognizer:pangr];}

target 是手势识别之后的处理者，这里就是view本身。

UIPangestureRecognizer的三个方法：

- (CGPoint)translationInView:(UIView *)aView;- (CGPoint)velocityInView:(UIView *)aView;- (void)setTranslation:(CGPoint)translation inView:(UIView *)aView;

第一个告诉移动的距离

第二个告诉移动的速度

第三个是重新设置

手势识别的状态机

@property (readonly) UIGestureRecognizerState state;

状态从possible  如果手势比较短：recognized    如果持续：Began - Changed  ,最后Ended

还有Failed 和 Cancelled状态，取消或其他操作中断时会有这个情况。

pan:是什么样的呢：

- (void)pan:(UIPanGestureRecognizer *)recognizer{if ((recognizer.state == UIGestureRecognizerStateChanged) ||(recognizer.state == UIGestureRecognizerStateEnded)) {   CGPoint translation = [recognizer translationInView:self];   // move something in myself (I’m a UIView) by translation.x and translation.y   // for example, if I were a graph and my origin was set by an @property called origin   self.origin = CGPointMake(self.origin.x+translation.x, self.origin.y+translation.y);   [recognizer setTranslation:CGPointZero inView:self];  } }

其他实例的手势：

UIPinchGestureRecognizer 缩放

UIRotationGestureRecognizer 旋转手势，两个手指按下，然后旋转，是个弧度，不是角度。

UISwipeGestureRecognizer    滑动手势， 一个或多个手指滑动，

UITapGestureRecognizer  点击手势

4、一个幸福笑脸的Demo:

内容介绍：

Model是： int happiness

View是：自定义的view叫做FaceView

Controller是：HappinessViewController

观察内容有：

drawRect 包括绘制子程序， pop push context(环境)

Faceview委托的数据如何属于Controller的协议。

Controller处理手势，或者view处理手势

通过手势来改变幸福度。

用整数表示幸福度， 0表示悲伤， 100表示非常幸福。

有两个手势，一个被view处理，因为它只修改显示，另外一个被controller处理，它要修改model,修改幸福度。

主要源码：

happinessViewController.h

#import <UIKit/UIKit.h>@interface HappinessViewController : UIViewController@property (nonatomic) int happiness;  // 0 is sad; 100 is very happy@end

happinessViewController.m

#import "HappinessViewController.h"#import "FaceView.h"@interface HappinessViewController() <FaceViewDataSource>@property (nonatomic, weak) IBOutlet FaceView *faceView;@end@implementation HappinessViewController@synthesize happiness = _happiness;@synthesize faceView = _faceView;- (void)setHappiness:(int)happiness{    _happiness = happiness;    [self.faceView setNeedsDisplay]; // any time our Model changes, redraw our View}- (void)setFaceView:(FaceView *)faceView{    _faceView = faceView;    // enable pinch gestures in the FaceView using its pinch: handler    [self.faceView addGestureRecognizer:[[UIPinchGestureRecognizer alloc] initWithTarget:self.faceView action:@selector(pinch:)]];    [self.faceView addGestureRecognizer:[[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleHappinessGesture:)]];  // gesture to modify our Model    self.faceView.dataSource = self;}- (void)handleHappinessGesture:(UIPanGestureRecognizer *)gesture{    if ((gesture.state == UIGestureRecognizerStateChanged) ||        (gesture.state == UIGestureRecognizerStateEnded)) {        CGPoint translation = [gesture translationInView:self.faceView];        self.happiness -= translation.y / 2;        [gesture setTranslation:CGPointZero inView:self.faceView];    }}- (float)smileForFaceView:(FaceView *)sender{    return (self.happiness - 50) / 50.0; // translate Model for View}- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation{    return YES; // support all orientations}@end

FaceView.h

#import <UIKit/UIKit.h>@class FaceView;  // forward declaration for use in @protocol@protocol FaceViewDataSource- (float)smileForFaceView:(FaceView *)sender;@end@interface FaceView : UIView@property (nonatomic) CGFloat scale;- (void)pinch:(UIPinchGestureRecognizer *)gesture;  // resizes the face// set this property to whatever object will provide this View's data// usually a Controller using a FaceView in its View@property (nonatomic, weak) IBOutlet id <FaceViewDataSource> dataSource;@end

FaceView.m

#import "FaceView.h"@implementation FaceView@synthesize dataSource = _dataSource;@synthesize scale = _scale;#define DEFAULT_SCALE 0.90- (CGFloat)scale{    if (!_scale) {        return DEFAULT_SCALE; // don't allow zero scale    } else {        return _scale;    }}- (void)setScale:(CGFloat)scale{    if (scale != _scale) {        _scale = scale;        [self setNeedsDisplay]; // any time our scale changes, call for redraw    }}- (void)pinch:(UIPinchGestureRecognizer *)gesture{    if ((gesture.state == UIGestureRecognizerStateChanged) ||        (gesture.state == UIGestureRecognizerStateEnded)) {        self.scale *= gesture.scale; // adjust our scale        gesture.scale = 1;           // reset gestures scale to 1 (so future changes are incremental, not cumulative)    }}- (void)setup{    self.contentMode = UIViewContentModeRedraw; // if our bounds changes, redraw ourselves}- (void)awakeFromNib{    [self setup]; // get initialized when we come out of a storyboard}- (id)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        [self setup]; // get initialized if someone uses alloc/initWithFrame: to create us    }    return self;}- (void)drawCircleAtPoint:(CGPoint)p withRadius:(CGFloat)radius inContext:(CGContextRef)context{    UIGraphicsPushContext(context);    CGContextBeginPath(context);    CGContextAddArc(context, p.x, p.y, radius, 0, 2*M_PI, YES); // 360 degree (0 to 2pi) arc    CGContextStrokePath(context);    UIGraphicsPopContext();}- (void)drawRect:(CGRect)rect{    CGContextRef context = UIGraphicsGetCurrentContext();        CGPoint midPoint; // center of our bounds in our coordinate system    midPoint.x = self.bounds.origin.x + self.bounds.size.width/2;    midPoint.y = self.bounds.origin.y + self.bounds.size.height/2;        CGFloat size = self.bounds.size.width / 2;    if (self.bounds.size.height < self.bounds.size.width) size = self.bounds.size.height / 2;    size *= self.scale; // scale is percentage of full view size        CGContextSetLineWidth(context, 5.0);    [[UIColor blueColor] setStroke];        [self drawCircleAtPoint:midPoint withRadius:size inContext:context]; // head    #define EYE_H 0.35#define EYE_V 0.35#define EYE_RADIUS 0.10        CGPoint eyePoint;    eyePoint.x = midPoint.x - size * EYE_H;    eyePoint.y = midPoint.y - size * EYE_V;        [self drawCircleAtPoint:eyePoint withRadius:size * EYE_RADIUS inContext:context]; // left eye    eyePoint.x += size * EYE_H * 2;    [self drawCircleAtPoint:eyePoint withRadius:size * EYE_RADIUS inContext:context]; // right eye#define MOUTH_H 0.45#define MOUTH_V 0.40#define MOUTH_SMILE 0.25        CGPoint mouthStart;    mouthStart.x = midPoint.x - MOUTH_H * size;    mouthStart.y = midPoint.y + MOUTH_V * size;    CGPoint mouthEnd = mouthStart;    mouthEnd.x += MOUTH_H * size * 2;    CGPoint mouthCP1 = mouthStart;    mouthCP1.x += MOUTH_H * size * 2/3;    CGPoint mouthCP2 = mouthEnd;    mouthCP2.x -= MOUTH_H * size * 2/3;        float smile = [self.dataSource smileForFaceView:self];    if (smile < -1) smile = -1;    if (smile > 1) smile = 1;        CGFloat smileOffset = MOUTH_SMILE * size * smile;    mouthCP1.y += smileOffset;    mouthCP2.y += smileOffset;        CGContextBeginPath(context);    CGContextMoveToPoint(context, mouthStart.x, mouthStart.y);    CGContextAddCurveToPoint(context, mouthCP1.x, mouthCP2.y, mouthCP2.x, mouthCP2.y, mouthEnd.x, mouthEnd.y); // bezier curve    CGContextStrokePath(context);}@end

容芳志 (http://blog.csdn.net/totogo2010)

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