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iOS 手势操作：拖动、捏合、旋转、点按、长按、轻扫、自定义

1、UIGestureRecognizer 介绍

手势识别在 iOS 中非常重要，他极大地提高了移动设备的使用便捷性。

iOS 系统在 3.2 以后，他提供了一些常用的手势（UIGestureRecognizer 的子类），开发者可以直接使用他们进行手势操作。

UIPanGestureRecognizer（拖动）
UIPinchGestureRecognizer（捏合）
UIRotationGestureRecognizer（旋转）
UITapGestureRecognizer（点按）
UILongPressGestureRecognizer（长按）
UISwipeGestureRecognizer（轻扫）

另外，可以通过继承 UIGestureRecognizer 类，实现自定义手势（手势识别器类）。

PS：自定义手势时，需要 #import <UIKit/UIGestureRecognizerSubclass.h>，一般需实现如下方法：

1 - (void)reset; 2  3 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event; 4 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; 5 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event; 6 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event; 7 //以上方法在分类 UIGestureRecognizer (UIGestureRecognizerProtected) 中声明，更多方法声明请自行查看

UIGestureRecognizer 的继承关系如下：

iOS 手势操作：拖动、捏合、旋转、点按、长按、轻扫、自定义

2、手势状态

在六种手势识别中，只有一种手势是离散型手势，他就是 UITapGestureRecognizer。

离散型手势的特点就是：一旦识别就无法取消，而且只会调用一次手势操作事件（初始化手势时指定的回调方法）。

换句话说其他五种手势是连续型手势，而连续型手势的特点就是：会多次调用手势操作事件，而且在连续手势识别后可以取消手势。从下图可以看出两者调用操作事件的次数是不同的：

iOS 手势操作：拖动、捏合、旋转、点按、长按、轻扫、自定义

手势状态枚举如下：

1 typedef NS_ENUM(NSInteger, UIGestureRecognizerState) { 2     UIGestureRecognizerStatePossible,   // 尚未识别是何种手势操作（但可能已经触发了触摸事件），默认状态 3     UIGestureRecognizerStateBegan,      // 手势已经开始，此时已经被识别，但是这个过程中可能发生变化，手势操作尚未完成 4     UIGestureRecognizerStateChanged,    // 手势状态发生转变 5     UIGestureRecognizerStateEnded,      // 手势识别操作完成（此时已经松开手指） 6     UIGestureRecognizerStateCancelled,  // 手势被取消，恢复到默认状态 7     UIGestureRecognizerStateFailed,     // 手势识别失败，恢复到默认状态 8     UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded // 手势识别完成，同UIGestureRecognizerStateEnded 9 };

对于离散型手势 UITapGestureRecgnizer 要么被识别，要么失败，点按（假设点按次数设置为1，并且没有添加长按手势）下去一次不松开则此时什么也不会发生，松开手指立即识别并调用操作事件，并且状态为3（已完成）。
但是连续型手势要复杂一些，就拿旋转手势来说，如果两个手指点下去不做任何操作，此时并不能识别手势（因为我们还没旋转）但是其实已经触发了触摸开始事件，此时处于状态0；如果此时旋转会被识别，也就会调用对应的操作事件，同时状态变成1（手势开始），但是状态1只有一瞬间；紧接着状态变为2（因为我们的旋转需要持续一会），并且重复调用操作事件（如果在事件中打印状态会重复打印2）；松开手指，此时状态变为3，并调用1次操作事件。

3、使用手势的步骤

使用手势很简单，分为三步：

创建手势识别器对象实例。创建时，指定一个回调方法，当手势开始，改变、或结束时，执行回调方法。
设置手势识别器对象实例的相关属性（可选部分）
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，那就会执行回调方法。

PS：一个手势只能对应一个 View，但是一个 View 可以有多个手势。建议在真机上测试这些手势，模拟器操作不太方便，可能导致认为手势失效的情况。（模拟器测试捏合和旋转手势时，按住 option 键，再用触摸板或鼠标操作）

4、举例说明

功能描述：

附加到两个图片视图 UIImageView 的有『拖动』、『捏合』、『旋转』、『点按』；

而『轻扫』和『自定义手势 KMGestureRecognizer』附加在根视图 UIView 中。

拖动：进行当前图片视图位置移动
捏合：进行当前图片视图缩放
旋转：进行当前图片视图角度旋转
点按：双击恢复当前图片视图的缩放、角度旋转、不透明度
长按：设置当前图片视图的不透明度为0.7
轻扫：左右轻扫设置两个图片视图为居中，同时以垂直居中的特定偏移量定位
自定义手势：挠痒功能，左右扫动共3次或以上，设置两个图片视图为居中，同时以水平居中的特定偏移量定位

效果如下：

iOS 手势操作：拖动、捏合、旋转、点按、长按、轻扫、自定义

KMGestureRecognizer.h

 1 #import <UIKit/UIKit.h>  2   3 typedef NS_ENUM(NSUInteger, Direction) {  4     DirectionUnknown,  5     DirectionLeft,  6     DirectionRight  7 };  8   9 @interface KMGestureRecognizer : UIGestureRecognizer 10 @property (assign, nonatomic) NSUInteger tickleCount; //挠痒次数 11 @property (assign, nonatomic) CGPoint currentTickleStart; //当前挠痒开始坐标位置 12 @property (assign, nonatomic) Direction lastDirection; //最后一次挠痒方向 13  14 @end

KMGestureRecognizer.m

 1 #import "KMGestureRecognizer.h"  2 #import <UIKit/UIGestureRecognizerSubclass.h>  3   4 @implementation KMGestureRecognizer  5 #define kMinTickleSpacing 20.0  6 #define kMaxTickleCount 3  7   8 - (void)reset {  9     _tickleCount = 0; 10     _currentTickleStart = CGPointZero; 11     _lastDirection = DirectionUnknown; 12      13     if (self.state == UIGestureRecognizerStatePossible) { 14         self.state = UIGestureRecognizerStateFailed; 15     } 16 } 17  18 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 19     UITouch *touch = [touches anyObject]; 20     _currentTickleStart = [touch locationInView:self.view]; //设置当前挠痒开始坐标位置 21 } 22  23 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 24     //『当前挠痒开始坐标位置』和『移动后坐标位置』进行 X 轴值比较，得到是向左还是向右移动 25     UITouch *touch = [touches anyObject]; 26     CGPoint tickleEnd = [touch locationInView:self.view]; 27     CGFloat tickleSpacing = tickleEnd.x - _currentTickleStart.x; 28     Direction currentDirection = tickleSpacing < 0 ? DirectionLeft : DirectionRight; 29      30     //移动的 X 轴间距值是否符合要求，足够大 31     if (ABS(tickleSpacing) >= kMinTickleSpacing) { 32         //判断是否有三次不同方向的动作，如果有则手势结束，将执行回调方法 33         if (_lastDirection == DirectionUnknown || 34             (_lastDirection == DirectionLeft && currentDirection == DirectionRight) || 35             (_lastDirection == DirectionRight && currentDirection == DirectionLeft)) { 36             _tickleCount++; 37             _currentTickleStart = tickleEnd; 38             _lastDirection = currentDirection; 39              40             if (_tickleCount >= kMaxTickleCount && self.state == UIGestureRecognizerStatePossible) { 41                 self.state = UIGestureRecognizerStateEnded; 42                 //NSLog(@"自定义手势成功，将执行回调方法"); 43             } 44         } 45     } 46 } 47  48 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { 49     [self reset]; 50 } 51  52 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { 53     [self reset]; 54 } 55  56 @end

ViewController.h

1 #import <UIKit/UIKit.h> 2 #import "KMGestureRecognizer.h" 3  4 @interface ViewController : UIViewController 5 @property (strong, nonatomic) UIImageView *imgV; 6 @property (strong, nonatomic) UIImageView *imgV2; 7 @property (strong, nonatomic) KMGestureRecognizer *customGestureRecognizer; 8  9 @end

ViewController.m

  1 #import "ViewController.h"   2    3 @interface ViewController ()   4 - (void)handlePan:(UIPanGestureRecognizer *)recognizer;   5 - (void)handlePinch:(UIPinchGestureRecognizer *)recognizer;   6 - (void)handleRotation:(UIRotationGestureRecognizer *)recognizer;   7 - (void)handleTap:(UITapGestureRecognizer *)recognizer;   8 - (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer;   9 - (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer;  10 - (void)handleCustomGestureRecognizer:(KMGestureRecognizer *)recognizer;  11   12 - (void)bindPan:(UIImageView *)imgVCustom;  13 - (void)bindPinch:(UIImageView *)imgVCustom;  14 - (void)bindRotation:(UIImageView *)imgVCustom;  15 - (void)bindTap:(UIImageView *)imgVCustom;  16 - (void)bindLongPress:(UIImageView *)imgVCustom;  17 - (void)bindSwipe;  18 - (void)bingCustomGestureRecognizer;  19 - (void)layoutUI;  20 @end  21   22 @implementation ViewController  23   24 - (void)viewDidLoad {  25     [super viewDidLoad];  26       27     [self layoutUI];  28 }  29   30 - (void)didReceiveMemoryWarning {  31     [super didReceiveMemoryWarning];  32     // Dispose of any resources that can be recreated.  33 }  34   35 #pragma mark - 处理手势操作  36 /**  37  *  处理拖动手势  38  *  39  *  @param recognizer 拖动手势识别器对象实例  40  */  41 - (void)handlePan:(UIPanGestureRecognizer *)recognizer {  42     //视图前置操作  43     [recognizer.view.superview bringSubviewToFront:recognizer.view];  44       45     CGPoint center = recognizer.view.center;  46     CGFloat cornerRadius = recognizer.view.frame.size.width / 2;  47     CGPoint translation = [recognizer translationInView:self.view];  48     //NSLog(@"%@", NSStringFromCGPoint(translation));  49     recognizer.view.center = CGPointMake(center.x + translation.x, center.y + translation.y);  50     [recognizer setTranslation:CGPointZero inView:self.view];  51       52     if (recognizer.state == UIGestureRecognizerStateEnded) {  53         //计算速度向量的长度，当他小于200时，滑行会很短  54         CGPoint velocity = [recognizer velocityInView:self.view];  55         CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));  56         CGFloat slideMult = magnitude / 200;  57         //NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); //e.g. 397.973175, slideMult: 1.989866  58           59         //基于速度和速度因素计算一个终点  60         float slideFactor = 0.1 * slideMult;  61         CGPoint finalPoint = CGPointMake(center.x + (velocity.x * slideFactor),  62                                          center.y + (velocity.y * slideFactor));  63         //限制最小［cornerRadius］和最大边界值［self.view.bounds.size.width - cornerRadius］，以免拖动出屏幕界限  64         finalPoint.x = MIN(MAX(finalPoint.x, cornerRadius),  65                            self.view.bounds.size.width - cornerRadius);  66         finalPoint.y = MIN(MAX(finalPoint.y, cornerRadius),  67                            self.view.bounds.size.height - cornerRadius);  68           69         //使用 UIView 动画使 view 滑行到终点  70         [UIView animateWithDuration:slideFactor*2  71                               delay:0  72                             options:UIViewAnimationOptionCurveEaseOut  73                          animations:^{  74                              recognizer.view.center = finalPoint;  75                          }  76                          completion:nil];  77     }  78 }  79   80 /**  81  *  处理捏合手势  82  *  83  *  @param recognizer 捏合手势识别器对象实例  84  */  85 - (void)handlePinch:(UIPinchGestureRecognizer *)recognizer {  86     CGFloat scale = recognizer.scale;  87     recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, scale, scale); //在已缩放大小基础下进行累加变化；区别于：使用 CGAffineTransformMakeScale 方法就是在原大小基础下进行变化  88     recognizer.scale = 1.0;  89 }  90   91 /**  92  *  处理旋转手势  93  *  94  *  @param recognizer 旋转手势识别器对象实例  95  */  96 - (void)handleRotation:(UIRotationGestureRecognizer *)recognizer {  97     recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);  98     recognizer.rotation = 0.0;  99 } 100  101 /** 102  *  处理点按手势 103  * 104  *  @param recognizer 点按手势识别器对象实例 105  */ 106 - (void)handleTap:(UITapGestureRecognizer *)recognizer { 107     UIView *view = recognizer.view; 108     view.transform = CGAffineTransformMakeScale(1.0, 1.0); 109     view.transform = CGAffineTransformMakeRotation(0.0); 110     view.alpha = 1.0; 111 } 112  113 /** 114  *  处理长按手势 115  * 116  *  @param recognizer 点按手势识别器对象实例 117  */ 118 - (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer { 119     //长按的时候，设置不透明度为0.7 120     recognizer.view.alpha = 0.7; 121 } 122  123 /** 124  *  处理轻扫手势 125  * 126  *  @param recognizer 轻扫手势识别器对象实例 127  */ 128 - (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer { 129     //代码块方式封装操作方法 130     void (^positionOperation)() = ^() { 131         CGPoint newPoint = recognizer.view.center; 132         newPoint.y -= 20.0; 133         _imgV.center = newPoint; 134          135         newPoint.y += 40.0; 136         _imgV2.center = newPoint; 137     }; 138      139     //根据轻扫方向，进行不同控制 140     switch (recognizer.direction) { 141         case UISwipeGestureRecognizerDirectionRight: { 142             positionOperation(); 143             break; 144         } 145         case UISwipeGestureRecognizerDirectionLeft: { 146             positionOperation(); 147             break; 148         } 149         case UISwipeGestureRecognizerDirectionUp: { 150             break; 151         } 152         case UISwipeGestureRecognizerDirectionDown: { 153             break; 154         } 155     } 156 } 157  158 /** 159  *  处理自定义手势 160  * 161  *  @param recognizer 自定义手势识别器对象实例 162  */ 163 - (void)handleCustomGestureRecognizer:(KMGestureRecognizer *)recognizer { 164     //代码块方式封装操作方法 165     void (^positionOperation)() = ^() { 166         CGPoint newPoint = recognizer.view.center; 167         newPoint.x -= 20.0; 168         _imgV.center = newPoint; 169          170         newPoint.x += 40.0; 171         _imgV2.center = newPoint; 172     }; 173      174     positionOperation(); 175 } 176  177  178 #pragma mark - 绑定手势操作 179 /** 180  *  绑定拖动手势 181  * 182  *  @param imgVCustom 绑定到图片视图对象实例 183  */ 184 - (void)bindPan:(UIImageView *)imgVCustom { 185     UIPanGestureRecognizer *recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self 186                                                                                  action:@selector(handlePan:)]; 187     [imgVCustom addGestureRecognizer:recognizer]; 188 } 189  190 /** 191  *  绑定捏合手势 192  * 193  *  @param imgVCustom 绑定到图片视图对象实例 194  */ 195 - (void)bindPinch:(UIImageView *)imgVCustom { 196     UIPinchGestureRecognizer *recognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self 197                                                                                      action:@selector(handlePinch:)]; 198     [imgVCustom addGestureRecognizer:recognizer]; 199     //[recognizer requireGestureRecognizerToFail:imgVCustom.gestureRecognizers.firstObject]; 200 } 201  202 /** 203  *  绑定旋转手势 204  * 205  *  @param imgVCustom 绑定到图片视图对象实例 206  */ 207 - (void)bindRotation:(UIImageView *)imgVCustom { 208     UIRotationGestureRecognizer *recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self 209                                                                                            action:@selector(handleRotation:)]; 210     [imgVCustom addGestureRecognizer:recognizer]; 211 } 212  213 /** 214  *  绑定点按手势 215  * 216  *  @param imgVCustom 绑定到图片视图对象实例 217  */ 218 - (void)bindTap:(UIImageView *)imgVCustom { 219     UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self 220                                                                                  action:@selector(handleTap:)]; 221     //使用一根手指双击时，才触发点按手势识别器 222     recognizer.numberOfTapsRequired = 2; 223     recognizer.numberOfTouchesRequired = 1; 224     [imgVCustom addGestureRecognizer:recognizer]; 225 } 226  227 /** 228  *  绑定长按手势 229  * 230  *  @param imgVCustom 绑定到图片视图对象实例 231  */ 232 - (void)bindLongPress:(UIImageView *)imgVCustom { 233     UILongPressGestureRecognizer *recognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)]; 234     recognizer.minimumPressDuration = 0.5; //设置最小长按时间；默认为0.5秒 235     [imgVCustom addGestureRecognizer:recognizer]; 236 } 237  238 /** 239  *  绑定轻扫手势；支持四个方向的轻扫，但是不同的方向要分别定义轻扫手势 240  */ 241 - (void)bindSwipe { 242     //向右轻扫手势 243     UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self 244                                                                                      action:@selector(handleSwipe:)]; 245     recognizer.direction = UISwipeGestureRecognizerDirectionRight; //设置轻扫方向；默认是 UISwipeGestureRecognizerDirectionRight，即向右轻扫 246     [self.view addGestureRecognizer:recognizer]; 247     [recognizer requireGestureRecognizerToFail:_customGestureRecognizer]; //设置以自定义挠痒手势优先识别 248      249     //向左轻扫手势 250     recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self 251                                                            action:@selector(handleSwipe:)]; 252     recognizer.direction = UISwipeGestureRecognizerDirectionLeft; 253     [self.view addGestureRecognizer:recognizer]; 254     [recognizer requireGestureRecognizerToFail:_customGestureRecognizer]; //设置以自定义挠痒手势优先识别 255 } 256  257 /** 258  *  绑定自定义挠痒手势；判断是否有三次不同方向的动作，如果有则手势结束，将执行回调方法 259  */ 260 - (void)bingCustomGestureRecognizer { 261     //当 recognizer.state 为 UIGestureRecognizerStateEnded 时，才执行回调方法 handleCustomGestureRecognizer: 262      263     //_customGestureRecognizer = [KMGestureRecognizer new]; 264     _customGestureRecognizer = [[KMGestureRecognizer alloc] initWithTarget:self 265                                                                     action:@selector(handleCustomGestureRecognizer:)]; 266     [self.view addGestureRecognizer:_customGestureRecognizer]; 267 } 268  269 - (void)layoutUI { 270     //图片视图 _imgV 271     UIImage *img = [UIImage imageNamed:@"Emoticon_tusiji_icon"]; 272     CGFloat cornerRadius = img.size.width; 273     _imgV = [[UIImageView alloc] initWithImage:img]; 274     _imgV.frame = CGRectMake(20.0, 20.0, 275                              cornerRadius * 2, cornerRadius * 2); 276     _imgV.userInteractionEnabled = YES; 277     _imgV.layer.masksToBounds = YES; 278     _imgV.layer.cornerRadius = cornerRadius; 279     _imgV.layer.borderWidth = 2.0; 280     _imgV.layer.borderColor = [UIColor grayColor].CGColor; 281     [self.view addSubview:_imgV]; 282      283     //图片视图 _imgV2 284     img = [UIImage imageNamed:@"Emoticon_tusiji_icon2"]; 285     cornerRadius = img.size.width; 286     _imgV2 = [[UIImageView alloc] initWithImage:img]; 287     _imgV2.frame = CGRectMake(20.0, 40.0 + _imgV.frame.size.height, 288                               cornerRadius * 2, cornerRadius * 2); 289     _imgV2.userInteractionEnabled = YES; 290     _imgV2.layer.masksToBounds = YES; 291     _imgV2.layer.cornerRadius = cornerRadius; 292     _imgV2.layer.borderWidth = 2.0; 293     _imgV2.layer.borderColor = [UIColor orangeColor].CGColor; 294     [self.view addSubview:_imgV2]; 295      296      297     [self bindPan:_imgV]; 298     [self bindPinch:_imgV]; 299     [self bindRotation:_imgV]; 300     [self bindTap:_imgV]; 301     [self bindLongPress:_imgV]; 302      303     [self bindPan:_imgV2]; 304     [self bindPinch:_imgV2]; 305     [self bindRotation:_imgV2]; 306     [self bindTap:_imgV2]; 307     [self bindLongPress:_imgV2]; 308      309     //为了处理手势识别优先级的问题，这里需先绑定自定义挠痒手势 310     [self bingCustomGestureRecognizer]; 311     [self bindSwipe]; 312 } 313  314 @end