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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UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] init];

[tapGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];

[tapGestureRecognizer setNumberOfTapsRequired:2];

[tapGestureRecognizer setNumberOfTouchesRequired:2];

[self.view addGestureRecognizer:tapGestureRecognizer];

[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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UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] init];

[pinchGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];

[self.view addGestureRecognizer:pinchGestureRecognizer];

[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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UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] init];

[panGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];

[panGestureRecognizer setMinimumNumberOfTouches:1];

[panGestureRecognizer setMaximumNumberOfTouches:5];

[self.view addGestureRecognizer:panGestureRecognizer];

[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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UISwipeGestureRecognizer *swipeGestureRecognizer = [[UISwipeGestureRecognizer alloc] init];

[swipeGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];

[swipeGestureRecognizer setNumberOfTouchesRequired:2];

[swipeGestureRecognizer setDirection:UISwipeGestureRecognizerDirectionRight];

[self.view addGestureRecognizer:swipeGestureRecognizer];

[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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UIRotationGestureRecognizer *rotationGestureRecognizer = [[UIRotationGestureRecognizer alloc] init];

[rotationGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];

[self.view addGestureRecognizer:rotationGestureRecognizer];

[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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UILongPressGestureRecognizer *longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] init];

[longPressGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];

[longPressGestureRecognizer setMinimumPressDuration:1.0f];

[longPressGestureRecognizer setAllowableMovement:50.0];

[self.view addGestureRecognizer:longPressGestureRecognizer];

[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];