iOS 手势操作：拖动、捏合、旋转、点按、长按、轻扫、自定义

jopen 9年前

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：

  1. 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。
  2. 设置手势识别器对象实例的相关属性（可选部分）
  3. 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。

  1. 拖动：进行当前图片视图位置移动
  2. 捏合：进行当前图片视图缩放
  3. 旋转：进行当前图片视图角度旋转
  4. 点按：双击恢复当前图片视图的缩放、角度旋转、不透明度
  5. 长按：设置当前图片视图的不透明度为0.7
  6. 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
  7. 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
来源：KenmuHuang