iOS--------手势识别的详细使用：拖动、缩放、旋转、点击、手势依赖、自定义手势

1、UIGestureRecognizer介绍

手势识别在iOS上非常重要，手势操作移动设备的重要特征，极大的增加了移动设备使用便捷性。

iOS系统在3.2以后，为方便开发这使用一些常用的手势，提供了UIGestureRecognizer类。手势识别UIGestureRecognizer类是个抽象类，下面的子类是具体的手势，开发这可以直接使用这些手势识别。

上面的手势对应的操作是：

Tap（点一下）
Pinch（二指往內或往外拨动，平时经常用到的缩放）
Rotation（旋转）
Swipe（滑动，快速移动）
Pan （拖移，慢速移动）
LongPress（长按）

UIGestureRecognizer的继承关系如下：

2、使用手势的步骤

使用手势很简单，分为两步：

创建手势实例。当创建手势时，指定一个回调方法，当手势开始，改变、或结束时，回调方法被调用。
添加到需要识别的View中。每个手势只对应一个View，当屏幕触摸在View的边界内时，如果手势和预定的一样，那就会回调方法。

ps：一个手势只能对应一个View，但是一个View可以有多个手势。

建议在真机上运行这些手势,模拟器操作不太方便，可能导致你认为手势失效。

3、Pan 拖动手势：

UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];

snakeImageView.frame = CGRectMake(50, 50, 100, 160);

UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]

initWithTarget:self

action:@selector(handlePan:)];

[snakeImageView addGestureRecognizer:panGestureRecognizer];

[self.view setBackgroundColor:[UIColor whiteColor]];

[self.view addSubview:snakeImageView];

新建一个ImageView，然后添加手势

回调方法：

- (void) handlePan:(UIPanGestureRecognizer*) recognizer

{

CGPoint translation = [recognizer translationInView:self.view];

recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,

recognizer.view.center.y + translation.y);

[recognizer setTranslation:CGPointZero inView:self.view];

}

4、Pinch缩放手势

UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]

initWithTarget:self

action:@selector(handlePinch:)];[snakeImageView addGestureRecognizer:pinchGestureRecognizer];

- (void) handlePinch:(UIPinchGestureRecognizer*) recognizer

{

recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);

recognizer.scale = 1;

}

5、Rotation旋转手势

UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]

initWithTarget:self

action:@selector(handleRotate:)];

[snakeImageView addGestureRecognizer:rotateRecognizer];

- (void) handleRotate:(UIRotationGestureRecognizer*) recognizer

{

recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);

recognizer.rotation = 0;

}

添加了这几个手势后，运行看效果，程序中的imageView放了一个

/^\/^\

_|__| O|

\/ /~ \_/ \

\____|__________/ \

\_______ \

`\ \ \

| | \

/ / \

/ / \\

/ / \ \

/ / _—-_ \ \

/ / _-~ ~-_ | |

( ( _-~ _–_ ~-_ _/ |

\ ~-____-~ _-~ ~-_ ~-_-~ /

~-_ _-~ ~-_ _-~

~–______-~ ~-___-~

的图片，在模拟器上拖动是没问题的。缩放和旋转有点问题，估计是因为在模拟器上的模拟的两个接触点距离在imageView的边界外了，所以操作无效果。

建议在真机上运行这个手势。

在模拟器上缩放和选择的操作技巧：

可以把imageView的frame值设置大一点，按住alt键，按下触摸板(不按下不行)，这样就可以旋转和缩放了。

6、添加第二个ImagView并添加手势

记住：一个手势只能添加到一个View，两个View当然要有两个手势的实例了

- (void)viewDidLoad

{

[super viewDidLoad];

UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];

UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]];

snakeImageView.frame = CGRectMake(120, 120, 100, 160);

dragonImageView.frame = CGRectMake(50, 50, 100, 160);

[self.view addSubview:snakeImageView];

[self.view addSubview:dragonImageView];

for (UIView *view in self.view.subviews) {

UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]

initWithTarget:self

action:@selector(handlePan:)];

UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]

initWithTarget:self

action:@selector(handlePinch:)];

UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]

initWithTarget:self

action:@selector(handleRotate:)];

[view addGestureRecognizer:panGestureRecognizer];

[view addGestureRecognizer:pinchGestureRecognizer];

[view addGestureRecognizer:rotateRecognizer];

[view setUserInteractionEnabled:YES];

}

[self.view setBackgroundColor:[UIColor whiteColor]];

}

多添加了一条龙的view，两个view都能接收上面的三种手势。运行效果如下：

7、拖动(pan手势)速度(以较快的速度拖放后view有滑行的效果)

如何实现呢？

监视手势是否结束
监视触摸的速度

- (void) handlePan:(UIPanGestureRecognizer*) recognizer

{

CGPoint translation = [recognizer translationInView:self.view];

recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,

recognizer.view.center.y + translation.y);

[recognizer setTranslation:CGPointZero inView:self.view];

if (recognizer.state == UIGestureRecognizerStateEnded) {

CGPoint velocity = [recognizer velocityInView:self.view];

CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));

CGFloat slideMult = magnitude / 200;

NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);

float slideFactor = 0.1 * slideMult; // Increase for more of a slide

CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor),

recognizer.view.center.y + (velocity.y * slideFactor));

finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);

finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);

[UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{

recognizer.view.center = finalPoint;

} completion:nil];

}

代码实现解析：

计算速度向量的长度（估计大部分都忘了）这些知识了。
如果速度向量小于200，那就会得到一个小于的小数，那么滑行会很短
基于速度和速度因素计算一个终点
确保终点不会跑出父View的边界
使用UIView动画使view滑动到终点

运行后，快速拖动图像view放开会看到view还会在原来的方向滑行一段路。

8、同时触发两个view的手势

手势之间是互斥的，如果你想同时触发蛇和龙的view，那么需要实现协议UIGestureRecognizerDelegate，

1 2	@interface ViewController : UIViewController<UIGestureRecognizerDelegate> @end

并在协议这个方法里返回YES。

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer

{

return YES;

}

把self作为代理设置给手势：

panGestureRecognizer.delegate = self;

pinchGestureRecognizer.delegate = self;

rotateRecognizer.delegate = self;

这样可以同时拖动或旋转缩放两个view了。

9、tap点击手势

这里为了方便看到tap的效果，当点击一下屏幕时，播放一个声音。

为了播放声音，我们加入AVFoundation.framework这个框架。

- (AVAudioPlayer *)loadWav:(NSString *)filename {

NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"];

NSError * error;

AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];

if (!player) {

NSLog(@"Error loading %@: %@", url, error.localizedDescription);

} else {

[player prepareToPlay];

}

return player;

}

我会在最后例子代码给出完整代码，添加手势的步骤和前面一样的。

#import <UIKit/UIKit.h>

#import <AVFoundation/AVFoundation.h>

@interface ViewController : UIViewController<UIGestureRecognizerDelegate>

@property (strong) AVAudioPlayer * chompPlayer;

@property (strong) AVAudioPlayer * hehePlayer;

@end

- (void)handleTap:(UITapGestureRecognizer *)recognizer {

[self.chompPlayer play];

}

运行，点一下某个图，就会播放一个咬东西的声音。

不过这个点击播放声音有点缺陷，就是在慢慢拖动的时候也会播放。这使得两个手势重合了。怎么解决呢？使用手势的：requireGestureRecognizerToFail方法。

10、手势的依赖性

在viewDidLoad的循环里添加这段代码：

1	[tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer];

意思就是，当如果pan手势失败，就是没发生拖动，才会出发tap手势。这样如果你有轻微的拖动，那就是pan手势发生了。tap的声音就不会发出来了。

11、自定义手势

自定义手势继承：UIGestureRecognizer，实现下面的方法：

– touchesBegan:withEvent:

– touchesMoved:withEvent:

– touchesEnded:withEvent:

- touchesCancelled:withEvent:

新建一个类，继承UIGestureRecognizer，代码如下：

.h文件

#import <UIKit/UIKit.h>

typedef enum {

DirectionUnknown = 0,

DirectionLeft,

DirectionRight

} Direction;

@interface HappyGestureRecognizer : UIGestureRecognizer

@property (assign) int tickleCount;

@property (assign) CGPoint curTickleStart;

@property (assign) Direction lastDirection;

@end

.m文件

#import "HappyGestureRecognizer.h"

#import <UIKit/UIGestureRecognizerSubclass.h>

#define REQUIRED_TICKLES 2

#define MOVE_AMT_PER_TICKLE 25

@implementation HappyGestureRecognizer

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

UITouch * touch = [touches anyObject];

self.curTickleStart = [touch locationInView:self.view];

}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

// Make sure we've moved a minimum amount since curTickleStart

UITouch * touch = [touches anyObject];

CGPoint ticklePoint = [touch locationInView:self.view];

CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x;

Direction curDirection;

if (moveAmt < 0) {

curDirection = DirectionLeft;

} else {

curDirection = DirectionRight;

}

if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return;

// 确认方向改变了

if (self.lastDirection == DirectionUnknown ||

(self.lastDirection == DirectionLeft && curDirection == DirectionRight) ||

(self.lastDirection == DirectionRight && curDirection == DirectionLeft)) {

// 挠痒次数

self.tickleCount++;

self.curTickleStart = ticklePoint;

self.lastDirection = curDirection;

// 一旦挠痒次数超过指定数，设置手势为结束状态

// 这样回调函数会被调用。

if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) {

[self setState:UIGestureRecognizerStateEnded];

}

- (void)reset {

self.tickleCount = 0;

self.curTickleStart = CGPointZero;

self.lastDirection = DirectionUnknown;

if (self.state == UIGestureRecognizerStatePossible) {

[self setState:UIGestureRecognizerStateFailed];

}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

{

[self reset];

}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event

{

[self reset];

}

@end

调用自定义手势和上面一样，回到这样写：

- (void)handleHappy:(HappyGestureRecognizer *)recognizer{

[self.hehePlayer play];

}

手势成功后播放呵呵笑的声音。
在真机上运行，按住某个view，快速左右拖动，就会发出笑的声音了。

代码解析：

先获取起始坐标：curTickleStart

通过和ticklePoint的x值对比，得出当前的放下是向左还是向右。再算出移动的x的值是否比MOVE_AMT_PER_TICKLE距离大，如果太则返回。

再判断是否有三次是不同方向的动作，如果是则手势结束，回调。

参考：http://www.raywenderlich.com/6567/uigesturerecognizer-tutorial-in-ios-5-pinches-pans-and-more