UITapGestureRecognizer

UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，它有6个子类处理具体的手势：

1.UITapGestureRecognizer （任意手指任意次数的点击）

// 点击次数

numberOfTapsRequired

// 手指个数

numberOfTouchesRequired   

 

 

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1. UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] init];  
2. [tapGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];  
3. [tapGestureRecognizer setNumberOfTapsRequired:2];  
4. [tapGestureRecognizer setNumberOfTouchesRequired:2];  
5. [self.view addGestureRecognizer:tapGestureRecognizer];  
6. [tapGestureRecognizer release];  

 

2.UIPinchGestureRecognizer （两个手指捏合动作）

 

// 手指捏合，大于1表示两个手指之间的距离变大，小于1表示两个手指之间的距离变小

scale

// 手指捏合动作时的速率（加速度）

velocity

 

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1. UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] init];  
2. [pinchGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];  
3. [self.view addGestureRecognizer:pinchGestureRecognizer];  
4. [pinchGestureRecognizer release];  

 

3.UIPanGestureRecognizer (摇动或者拖拽)

 

 

// 最少手指个数

minimumNumberOfTouches

// 最多手指个数

maximumNumberOfTouches

 

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1. UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] init];  
2. [panGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];  
3. [panGestureRecognizer setMinimumNumberOfTouches:1];  
4. [panGestureRecognizer setMaximumNumberOfTouches:5];  
5. [self.view addGestureRecognizer:panGestureRecognizer];  
6. [panGestureRecognizer release];  

 

4.UISwipeGestureRecognizer (手指在屏幕上滑动操作手势)

 

// 滑动手指的个数

numberOfTouchesRequired

// 手指滑动的方向 （Up,Down,Left,Right）

direction

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1. UISwipeGestureRecognizer *swipeGestureRecognizer = [[UISwipeGestureRecognizer alloc] init];  
2. [swipeGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];  
3. [swipeGestureRecognizer setNumberOfTouchesRequired:2];  
4. [swipeGestureRecognizer setDirection:UISwipeGestureRecognizerDirectionRight];  
5. [self.view addGestureRecognizer:swipeGestureRecognizer];  
6. [swipeGestureRecognizer release];  

5.UIRotationGestureRecognizer (手指在屏幕上旋转操作)

 

// 旋转方向，小于0为逆时针旋转手势，大于0为顺时针手势

rotation

// 旋转速率

velocity

 

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1. UIRotationGestureRecognizer *rotationGestureRecognizer = [[UIRotationGestureRecognizer alloc] init];  
2. [rotationGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];  
3. [self.view addGestureRecognizer:rotationGestureRecognizer];  
4. [rotationGestureRecognizer release];  

 

6.UILongPressGestureRecognizer (长按手势)

 

 

// Default is 0. The number of full taps required before the press for gesture to be recognized

numberOfTapsRequired

// 需要长按的手指的个数

numberOfTouchesRequired

// 需要长按的时间，最小为0.5s

minimumPressDuration

// 手指按住允许移动的距离

allowableMovement

 

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1. UILongPressGestureRecognizer *longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] init];  
2. [longPressGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];  
3. [longPressGestureRecognizer setMinimumPressDuration:1.0f];  
4. [longPressGestureRecognizer setAllowableMovement:50.0];  
5. [self.view addGestureRecognizer:longPressGestureRecognizer];  
6. [longPressGestureRecognizer release];  

tap是指轻触手势。类似鼠标操作的点击。从iOS 3.2版本开始支持完善的手势api：

    tap：轻触
    long press：在一点上长按
    pinch：两个指头捏或者放的操作
    pan：手指的拖动
    swipe：手指在屏幕上很快的滑动
    rotation：手指反向操作

这为开发者编写手势识别操作，提供了很大的方便，想想之前用android写手势滑动的代码（编写android简单的手势切换视图示例），尤其感到幸福。

这里写一个简单的tap操作。在下面视图的蓝色视图内增加对tap的识别：

image

 

当用手指tap蓝色视图的时候，打印日志输出：

image

代码很简单，首先要声明tap的recognizer：

    UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapFrom:)];
    [infoView addGestureRecognizer:recognizer];
    [recognizer release];

在这里：

    initWithTarget:self，要引用到Controller，因为一般这部分代码写在controller中，用self；
    action:@selector(handleTapFrom:)，赋值一个方法名，用于当手势事件发生后的回调；
    [infoView addGestureRecognizer:recognizer]，为view注册这个手势识别对象，这样当手指在该视图区域内，可引发手势，之外则不会引发

对应的回调方法：

    -(void)handleTapFrom:(UITapGestureRecognizer *)recognizer{
        NSLog(@">>>tap it");
    }

controller相关方法完整的代码（包含了一些与本文无关的视图构建代码）：

    // Implement loadView to create a view hierarchy programmatically, without using a nib.
    - (void)loadView {
        //去掉最顶端的状态拦
        [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation: UIStatusBarAnimationSlide];
       
        UIImage *image=[UIImage imageNamed:@"3.jpg"];
       
        //创建背景视图
        self.view=[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
        UIImageView *backgroudView=[[UIImageView alloc] initWithImage:image];
        [self.view addSubview:backgroudView];
       
       
       
        UIView *bottomView=[[UIView alloc]  initWithFrame:CGRectMake(0, 1024-70, 768, 70)];
        bottomView.backgroundColor=[UIColor grayColor];
        bottomView.alpha=0.8;
       
        //UIButton *backButton=[[UIButton alloc] initWithFrame:CGRectMake(10, 10, 100, 40)];
        UIButton *backButton=[UIButton buttonWithType: UIButtonTypeRoundedRect];
        [backButton setTitle:@"ok" forState:UIControlStateNormal];
        backButton.frame=CGRectMake(10, 15, 100, 40);
       
        [bottomView addSubview:backButton];
       
        [self.view addSubview:bottomView];
       
        UIView *infoView=[[UIView alloc] initWithFrame:CGRectMake(200, 700, 768-400, 70)];
        infoView.backgroundColor=[UIColor blueColor];
        infoView.alpha=0.6;
        infoView.layer.cornerRadius=6;
        infoView.layer.masksToBounds=YES;
        [self.view addSubview:infoView];
       
        UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapFrom:)];
        [infoView addGestureRecognizer:recognizer];
        [recognizer release];
    }

    -(void)handleTapFrom:(UITapGestureRecognizer *)recognizer{
        NSLog(@">>>tap it");
    }

     

     

     

     

    翻页效果，类似下面的样子：

    imageimage

    在电子书应用中会很常见。这里需要两个要点：

        翻页动画
        手势上下轻扫（swipe）的处理

     

    先说一下轻扫（swipe）的实现，可以参考编写简单的手势示例：Tap了解手势种类。

    在viewDidLoad方法中注册了对上、下、左、右四个方向轻松的处理方法：

        - (void)viewDidLoad {
           
            UISwipeGestureRecognizer *recognizer;
           
            recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
            [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
            [[self view] addGestureRecognizer:recognizer];
            [recognizer release];
           
            recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
            [recognizer setDirection:(UISwipeGestureRecognizerDirectionUp)];
            [[self view] addGestureRecognizer:recognizer];
            [recognizer release];
           
            recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
            [recognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];
            [[self view] addGestureRecognizer:recognizer];
            [recognizer release];
           
            recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
            [recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
            [[self view] addGestureRecognizer:recognizer];
            [recognizer release];
           
           
            [super viewDidLoad];

         

    可以看到，都是同一个方法，handleSwipeFrom。

    在该方法中，再识别具体是哪个方向的轻扫手势，比如判断是向下的轻扫：

        -(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {
            NSLog(@"Swipe received.");
           
            if (recognizer.direction==UISwipeGestureRecognizerDirectionDown) {
                NSLog(@"swipe down");

    判断是向上的轻扫：

        if (recognizer.direction==UISwipeGestureRecognizerDirectionUp) {
            NSLog(@"swipe up");

    有关动画的处理，比如向下（往回）翻页，类似这样：

        [UIView beginAnimations:@"animationID" context:nil];
        [UIView setAnimationDuration:0.7f];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
        [UIView setAnimationRepeatAutoreverses:NO];
        [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES];

        [currentView removeFromSuperview];
        [self.view addSubview:contentView];

        [UIView commitAnimations];

    向上（向前）翻页，只需改为：

        [UIView beginAnimations:@"animationID" context:nil];
        [UIView setAnimationDuration:0.7f];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
        [UIView setAnimationRepeatAutoreverses:NO];
        [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES];

        [currentView removeFromSuperview];
        [self.view addSubview:contentView];

        [UIView commitAnimations];

    如果是电子书，还需要考虑一个问题，就是有多个页面（图形），比如50页。那么需要有一个数据结构来保存这些页面的图片路径：

        objc数据结构，比如数组
        sqlite数据库表

    这样，写一套翻页代码和加载什么图形之间就可以解耦。

    本文示例使用的是数组，类似这样：

        pages=[[NSArray alloc] initWithObjects:@"1.jpg",@"2.jpg",@"3.jpg",@"4.jpg",@"5.jpg",@"6.jpg",
                         nil];

    图片保存在resources下。

    为了能让上页下页翻页的时候找到关联的页面，采用了如下机制：

        将图片封装为UIImageView显示
        可以为UIImageView设置一个tag值，值为数组下标+1
        这样，上级view有方法能根据tag查询到UIImageView，比如：UIView *currentView=[self.view viewWithTag:currentTag];
        设置一个成员变量currentTag保存当前的tag值

    比如这样，当应用加载的时候显示第一页：

            currentTag=1;
           
            NSString *path = [[NSBundle mainBundle] pathForResource:@"pageflip1" ofType:@"mp3"];
            player=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];
           
            //[[UIApplication sharedApplication] setStatusBarHidden:YES animated:NO];
            [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation: UIStatusBarAnimationSlide];
            UIImageView *contentView = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; 
            [contentView setImage:[UIImage imageNamed:[pages objectAtIndex:(currentTag-1)]]]; 
            [contentView setUserInteractionEnabled:YES];
            contentView.tag=currentTag;

    在翻页时的处理：

        if (currentTag<[pages count]) {
            UIView *currentView=[self.view viewWithTag:currentTag];
            currentTag++;
           
            UIImageView *contentView = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
            [contentView setImage:[UIImage imageNamed:[pages objectAtIndex:(currentTag-1)]]]; 
            [contentView setUserInteractionEnabled:YES];
            contentView.tag=currentTag;
           
            [UIView beginAnimations:@"animationID" context:nil];
            [UIView setAnimationDuration:0.7f];
            [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
            [UIView setAnimationRepeatAutoreverses:NO];
            [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES];
           
            [currentView removeFromSuperview];
            [self.view addSubview:contentView];
           
            [UIView commitAnimations];