【转】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)

2013-04-02 16:27 maying_07 阅读(221) 评论(0) 编辑收藏举报

原文地址：http://blog.csdn.net/totogo2010/article/details/8615940

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：

1     UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];
2     snakeImageView.frame = CGRectMake(50, 50, 100, 160);
3     UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]
4                                                     initWithTarget:self
5                                                     action:@selector(handlePan:)];    
6     [snakeImageView addGestureRecognizer:panGestureRecognizer];
7     [self.view setBackgroundColor:[UIColor whiteColor]];
8     [self.view addSubview:snakeImageView];

新建一个ImageView，然后添加手势

回调方法：

1 - (void) handlePan:(UIPanGestureRecognizer*) recognizer
2 {
3     CGPoint translation = [recognizer translationInView:self.view];
4     recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
5                                    recognizer.view.center.y + translation.y);
6     [recognizer setTranslation:CGPointZero inView:self.view];
7     
8 }

Pinch缩放手势

1 UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]
2 initWithTarget:self
3 action:@selector(handlePinch:)];
4 
5 [snakeImageView addGestureRecognizer:pinchGestureRecognizer];

1 - (void) handlePinch:(UIPinchGestureRecognizer*) recognizer
2 {
3     recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
4     recognizer.scale = 1;
5 }

5、Rotation旋转手势

1     UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]
2                                                      initWithTarget:self
3                                                      action:@selector(handleRotate:)];
4     [snakeImageView addGestureRecognizer:rotateRecognizer];

1 - (void) handleRotate:(UIRotationGestureRecognizer*) recognizer
2 {
3     recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
4     recognizer.rotation = 0;
5 }

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

 1 - (void)viewDidLoad
 2 {
 3     [super viewDidLoad];
 4 
 5     UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];
 6     UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]];
 7     snakeImageView.frame = CGRectMake(120, 120, 100, 160);
 8     dragonImageView.frame = CGRectMake(50, 50, 100, 160);
 9     [self.view addSubview:snakeImageView];
10     [self.view addSubview:dragonImageView];
11     
12     for (UIView *view in self.view.subviews) {
13         UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]
14                                                         initWithTarget:self
15                                                         action:@selector(handlePan:)];
16         
17         UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]
18                                                             initWithTarget:self
19                                                             action:@selector(handlePinch:)];
20         
21         UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]
22                                                          initWithTarget:self
23                                                          action:@selector(handleRotate:)];
24         
25         [view addGestureRecognizer:panGestureRecognizer];
26         [view addGestureRecognizer:pinchGestureRecognizer];
27         [view addGestureRecognizer:rotateRecognizer];
28         [view setUserInteractionEnabled:YES];
29     }
30     [self.view setBackgroundColor:[UIColor whiteColor]];     
31 }

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

 1 - (void) handlePan:(UIPanGestureRecognizer*) recognizer
 2 {
 3     CGPoint translation = [recognizer translationInView:self.view];
 4     recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
 5                                        recognizer.view.center.y + translation.y);
 6     [recognizer setTranslation:CGPointZero inView:self.view];
 7     
 8     if (recognizer.state == UIGestureRecognizerStateEnded) {
 9         
10         CGPoint velocity = [recognizer velocityInView:self.view];
11         CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
12         CGFloat slideMult = magnitude / 200;
13         NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);
14         
15         float slideFactor = 0.1 * slideMult; // Increase for more of a slide
16         CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor),
17                                          recognizer.view.center.y + (velocity.y * slideFactor));
18         finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);
19         finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);
20         
21         [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
22             recognizer.view.center = finalPoint;
23         } completion:nil];
24         
25     }
26

 1 代码实现解析：
 2 计算速度向量的长度（估计大部分都忘了）这些知识了。
 3 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
 4 基于速度和速度因素计算一个终点
 5 确保终点不会跑出父View的边界
 6 使用UIView动画使view滑动到终点
 7 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 
 9 8、同时触发两个view的手势
10 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
11 UIGestureRecognizerDelegate，

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

并在协议这个方法里返回YES。

1 -(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
2 {
3     return YES;
4 }

把self作为代理设置给手势：

1         panGestureRecognizer.delegate = self;
2         pinchGestureRecognizer.delegate = self;
3         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。

 1 - (AVAudioPlayer *)loadWav:(NSString *)filename {
 2     NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"];
 3     NSError * error;
 4     AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
 5     if (!player) {
 6         NSLog(@"Error loading %@: %@", url, error.localizedDescription);
 7     } else {
 8         [player prepareToPlay];
 9     }
10     return player;
11 }

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。

1 #import <UIKit/UIKit.h>
2 #import <AVFoundation/AVFoundation.h>
3 
4 @interface ViewController : UIViewController<UIGestureRecognizerDelegate>
5 @property (strong) AVAudioPlayer * chompPlayer;
6 @property (strong) AVAudioPlayer * hehePlayer;
7 
8 @end

1 - (void)handleTap:(UITapGestureRecognizer *)recognizer {
2     [self.chompPlayer play];
3 }

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：

1 – touchesBegan:withEvent:
2 – touchesMoved:withEvent:
3 – touchesEnded:withEvent:
4 - touchesCancelled:withEvent:

新建一个类，继承UIGestureRecognizer，代码如下：

.h文件

 1 #import <UIKit/UIKit.h>
 2 typedef enum {
 3     DirectionUnknown = 0,
 4     DirectionLeft,
 5     DirectionRight
 6 } Direction;
 7 
 8 @interface HappyGestureRecognizer : UIGestureRecognizer
 9 @property (assign) int tickleCount;
10 @property (assign) CGPoint curTickleStart;
11 @property (assign) Direction lastDirection;
12 
13 @end

.m文件

 1 #import "HappyGestureRecognizer.h"
 2 #import <UIKit/UIGestureRecognizerSubclass.h>
 3 #define REQUIRED_TICKLES        2
 4 #define MOVE_AMT_PER_TICKLE     25
 5 
 6 @implementation HappyGestureRecognizer
 7 
 8 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
 9     UITouch * touch = [touches anyObject];
10     self.curTickleStart = [touch locationInView:self.view];
11 }
12 
13 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
14     
15     // Make sure we've moved a minimum amount since curTickleStart
16     UITouch * touch = [touches anyObject];
17     CGPoint ticklePoint = [touch locationInView:self.view];
18     CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x;
19     Direction curDirection;
20     if (moveAmt < 0) {
21         curDirection = DirectionLeft;
22     } else {
23         curDirection = DirectionRight;
24     }
25     if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return;
26     
27     // 确认方向改变了
28     if (self.lastDirection == DirectionUnknown ||
29         (self.lastDirection == DirectionLeft && curDirection == DirectionRight) ||
30         (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) {
31         
32         // 挠痒次数
33         self.tickleCount++;
34         self.curTickleStart = ticklePoint;
35         self.lastDirection = curDirection;
36         
37         // 一旦挠痒次数超过指定数，设置手势为结束状态
38         // 这样回调函数会被调用。
39         if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) {
40             [self setState:UIGestureRecognizerStateEnded];
41         }
42     }
43     
44 }
45 
46 - (void)reset {
47     self.tickleCount = 0;
48     self.curTickleStart = CGPointZero;
49     self.lastDirection = DirectionUnknown;
50     if (self.state == UIGestureRecognizerStatePossible) {
51         [self setState:UIGestureRecognizerStateFailed];
52     }
53 }
54 
55 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
56 {
57     [self reset];
58 }
59 
60 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
61 {
62     [self reset];
63 }
64 
65 @end

调用自定义手势和上面一样，回到这样写：

1 - (void)handleHappy:(HappyGestureRecognizer *)recognizer{
2     [self.hehePlayer play];
3 }

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

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