iOS 手势UIGestureRecognizer

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在 iPhone 或 iPad 的开发中，除了用 touchesBegan / touchesMoved / touchesEnded 这组方法来控制使用者的手指触控外，也可以用 UIGestureRecognizer 的衍生类別来进行判断。用 UIGestureRecognizer 的好处在于有现成的手势，开发者不用自己计算手指移动轨迹。UIGestureRecognizer的衍生类別有以下几种：

UITapGestureRecognizer
UIPinchGestureRecognizer
UIRotationGestureRecognizer
UISwipeGestureRecognizer
UIPanGestureRecognizer
UILongPressGestureRecognizer

从命名上不难了解這些类別所对应代表的手势，分別是 Tap（点一下）、Pinch（二指往內或往外拨动）、Rotation（旋转）、Swipe（滑动，快速移动）、Pan （拖移，慢速移动）以及 LongPress（长按）。這些手势別在使用上也很简单，只要在使用前定义并添加到对应的视图上即可。

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// 定义一个 recognizer, 并加到需要偵測该手势的 UIView 元件上
- (void)viewDidLoad {
UISwipeGestureRecognizer* recognizer;
// handleSwipeFrom 是偵測到手势，所要呼叫的方法
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipeFrom)];
// 不同的 Recognizer 有不同的实体变数
// 例如 SwipeGesture 可以指定方向
// 而 TapGesture 則可以指定次數
recognizer.direction = UISwipeGestureRecognizerDirectionUp
[self.view addGestureRecognizer:recognizer];
[recognizer release];
}

- (void)handleSwipeFrom:(UISwipeGestureRecognizer*)recognizer {
// 触发手勢事件后，在这里作些事情

// 底下是刪除手势的方法
[self.view removeGestureRecognizer:recognizer];
}
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问题來了。有些手势其实是互相关联的，例如 Tap 与 LongPress、Swipe与 Pan，或是 Tap 一次与Tap 兩次。当一個 UIView 同时添加兩个相关联的手势时，到底我这一下手指头按的要算是 Tap 还是 LongPress？如果照預设作法来看，只要「先滿足条件」的就会跳出并呼叫对应方法，举例来说，如果同时注册了 Pan 和 Swipe，只要手指头一移动就会触发 Pan 然后跳出，因而永远都不會发生 Swipe；单点与双点的情形也是一样，永远都只会触发单点，不會有双点。

那么这个问题有解吗？答案是肯定的，UIGestureRecognizer 有个方法叫做requireGestureRecognizerToFail，他可以指定某一个 recognizer，即便自己已经滿足條件了，也不會立刻触发，会等到该指定的 recognizer 确定失败之后才触发。以同时支持单点与双点的手势为例，代码如下：

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- (void)viewDidLoad {
// 单击的 Recognizer
UITapGestureRecognizer* singleRecognizer;
singleRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSingleTapFrom)];
singleTapRecognizer.numberOfTapsRequired = 1; // 单击
[self.view addGestureRecognizer:singleRecognizer];

// 双击的 Recognizer
UITapGestureRecognizer* double;
doubleRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleDoubleTapFrom)];
doubleTapRecognizer.numberOfTapsRequired = 2; // 双击
[self.view addGestureRecognizer:doubleRecognizer];

// 关键在这一行，如果双击确定偵測失败才會触发单击
[singleRecognizer requireGestureRecognizerToFail:doubleRecognizer];
[singleRecognizer release];
[doubleRecognizer release];
}
Demo
首先新建一个基于Sigle view Application的项目，名为GestureTest;我的项目结构如下：

往viewController.xib文件里拖动一个imageView,并使覆盖整个屏幕，改动属性为：

viewController.h文件：

1. #import <UIKit/UIKit.h>

2.

3. @interface ViewController : UIViewController{

4. IBOutlet UIImageView *imageView;

5. }

6. @property (nonatomic,retain)IBOutlet UIImageView *imageView;

7. @end

并使xib文件里的imageView与之连接；

然后是viewController.m文件的实现部分：

1. @synthesize imageView;

2.

3. CGFloat lastScaleFactor=1;//放大、缩小

4. CGFloat netRotation;//旋转

5. CGPoint netTranslation;//平衡

6. NSArray *images;//图片数组

7. int imageIndex=0;//数组下标

8.

9. - (void)viewDidLoad

10. {

11. //1、创建手势实例，并连接方法handleTapGesture,点击手势

12. UITapGestureRecognizer *tapGesture=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handleTapGesture:)];

13. //设置手势点击数,双击：点2下

14. tapGesture.numberOfTapsRequired=2;

15. // imageView添加手势识别

16. [imageView addGestureRecognizer:tapGesture];

17. //释放内存

18. [tapGesture release];

19.

20. //2、手势为捏的姿势:按住option按钮配合鼠标来做这个动作在虚拟器上

21. UIPinchGestureRecognizer *pinchGesture=[[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinchGesture:)];

22. [imageView addGestureRecognizer:pinchGesture];//imageView添加手势识别

23. [pinchGesture release];

24.

25. //3、旋转手势:按住option按钮配合鼠标来做这个动作在虚拟器上

26. UIRotationGestureRecognizer *rotateGesture=[[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(handleRotateGesture:)];

27. [imageView addGestureRecognizer:rotateGesture];

28. [rotateGesture release];

29.

30. //4、拖手势

31. UIPanGestureRecognizer *panGesture=[[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePanGesture:)];

32. // [imageView addGestureRecognizer:panGesture];

33. [panGesture release];

34.

35. //5、划动手势

36. images=[[NSArray alloc]initWithObjects:@"cell.jpg",@"heihua.jpg",@"xuanyi.jpg", nil];

37. //右划

38. UISwipeGestureRecognizer *swipeGesture=[[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(handleSwipeGesture:)];

39. [imageView addGestureRecognizer:swipeGesture];

40. [swipeGesture release];

41. //左划

42. UISwipeGestureRecognizer *swipeLeftGesture=[[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(handleSwipeGesture:)];

43. swipeGesture.direction=UISwipeGestureRecognizerDirectionLeft;//不设置黑夜是右

44. [imageView addGestureRecognizer:swipeLeftGesture];

45. [swipeLeftGesture release];

46.

47. //6、长按手势

48. UILongPressGestureRecognizer *longpressGesutre=[[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(handleLongpressGesture:)];

49. //长按时间为1秒

50. longpressGesutre.minimumPressDuration=1;

51. //允许15秒中运动

52. longpressGesutre.allowableMovement=15;

53. //所需触摸1次

54. longpressGesutre.numberOfTouchesRequired=1;

55. [imageView addGestureRecognizer:longpressGesutre];

56. [longpressGesutre release];

57.

58. [super viewDidLoad];

59. // Do any additional setup after loading the view, typically from a nib.

60. }

61. //双击屏幕时会调用此方法,放大和缩小图片

62. -(IBAction)handleTapGesture:(UIGestureRecognizer*)sender{

63. //判断imageView的内容模式是否是UIViewContentModeScaleAspectFit,该模式是原比例，按照图片原时比例显示大小

64. if(sender.view.contentMode==UIViewContentModeScaleAspectFit){

65. //把imageView模式改成UIViewContentModeCenter，按照图片原先的大小显示中心的一部分在imageView

66. sender.view.contentMode=UIViewContentModeCenter;

67. }else{

68. sender.view.contentMode=UIViewContentModeScaleAspectFit;

69. }

70. }

71. //捏的手势，使图片放大和缩小，捏的动作是一个连续的动作

72. -(IBAction)handlePinchGesture:(UIGestureRecognizer*)sender{

73. //得到sender捏手势的大小

74. CGFloat factor=[(UIPinchGestureRecognizer*)sender scale];

75. if(factor>1){

76. //图片放大

77. sender.view.transform=CGAffineTransformMakeScale(lastScaleFactor+(factor-1), (lastScaleFactor+(factor-1)));

78.

79. }else{

80. //缩小

81. sender.view.transform=CGAffineTransformMakeScale(lastScaleFactor*factor, lastScaleFactor*factor);

82.

83. }

84. //状态是否结束，如果结束保存数据

85. if(sender.state==UIGestureRecognizerStateEnded){

86. if(factor>1){

87. lastScaleFactor+=(factor-1);

88. }else{

89. lastScaleFactor*=factor;

90. }

91. }

92. }

93. //旋转手势

94. -(IBAction)handleRotateGesture:(UIGestureRecognizer*)sender{

95. //浮点类型，得到sender的旋转度数

96. CGFloat rotation=[(UIRotationGestureRecognizer*)sender rotation];

97. //旋转角度CGAffineTransformMakeRotation

98. CGAffineTransform transform=CGAffineTransformMakeRotation(rotation+netRotation);

99. //改变图像角度

100. sender.view.transform=transform;

101. //状态结束，保存数据

102. if(sender.state==UIGestureRecognizerStateEnded){

103. netRotation+=rotation;

104. }

105.

106. }

107. //拖手势

108. -(IBAction)handlePanGesture:(UIGestureRecognizer*)sender{

109. //得到拖的过程中的xy坐标

110. CGPoint translation=[(UIPanGestureRecognizer*)sender translationInView:imageView];

111. //平移图片CGAffineTransformMakeTranslation

112. sender.view.transform=CGAffineTransformMakeTranslation(netTranslation.x+translation.x, netTranslation.y+translation.y);

113. //状态结束，保存数据

114. if(sender.state==UIGestureRecognizerStateEnded){

115. netTranslation.x+=translation.x;

116. netTranslation.y+=translation.y;

117. }

118.

119. }

120. //划动手势

121. -(IBAction)handleSwipeGesture:(UIGestureRecognizer*)sender{

122. //划动的方向

123. UISwipeGestureRecognizerDirection direction=[(UISwipeGestureRecognizer*) sender direction];

124. //判断是上下左右

125. switch (direction) {

126. case UISwipeGestureRecognizerDirectionUp:

127. NSLog(@"up");

128. break;

129. case UISwipeGestureRecognizerDirectionDown:

130. NSLog(@"down");

131. break;

132. case UISwipeGestureRecognizerDirectionLeft:

133. NSLog(@"left");

134. imageIndex++;//下标++

135. break;

136. case UISwipeGestureRecognizerDirectionRight:

137. NSLog(@"right");

138. imageIndex--;//下标--

139. break;

140. default:

141. break;

142. }

143. //得到不越界不<0的下标

144. imageIndex=(imageIndex<0)?([images count]-1):imageIndex%[images count];

145. //imageView显示图片

146. imageView.image=[UIImage imageNamed:[images objectAtIndex:imageIndex]];

147.

148. }

149. //长按手势

150. -(IBAction)handleLongpressGesture:(UIGestureRecognizer*)sender{

151. //创建警告

152. UIActionSheet *actionSheet=[[UIActionSheet alloc]initWithTitle:@"Image options" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:@"Save Image",@"Copy", nil];

153. //当前view显示警告

154. [actionSheet showInView:self.view];

155. [actionSheet release];

156. }

157. -(void)dealloc{

158. [images release];

159. [imageView release];

160. [super dealloc];

161. }

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