UIGestureRecognizer

为了完成手势识别，必须借助于手势识别器—-UIGestureRecognizer

利用UIGestureRecognizer，能轻松识别用户在某个view上面做的一些常见手势

UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，使用它的子类才能处理具体的手势

UITapGestureRecognizer       //(敲击)  UIPinchGestureRecognizer     //(捏合，用于缩放)  UIPanGestureRecognizer       //(拖拽)  UISwipeGestureRecognizer     //(轻扫)  UIRotationGestureRecognizer  //(旋转)  UILongPressGestureRecognizer //(长按)

敲击 UITapGestureRecognizer

每一个手势识别器的用法都差不多，比如UITapGestureRecognizer的使用步骤如下

创建手势识别器对象  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];    设置手势识别器对象的具体属性  // 连续敲击2次  tap.numberOfTapsRequired = 2;  // 需要2根手指一起敲击  tap.numberOfTouchesRequired = 2;    添加手势识别器到对应的view上  [self.iconView addGestureRecognizer:tap];    监听手势的触发  [tap addTarget:self action:@selector(tapIconView:)];

敲击实例

@interface GRViewController () <UIGestureRecognizerDelegate>  @property (weak, nonatomic) IBOutlet UIImageView *iconView;    @end    @implementation GRViewController    - (void)viewDidLoad  {      [super viewDidLoad];        [self testTap2];  }    - (void)testTap2  {      UIGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapView)];      tap.delegate = self;      [self.iconView addGestureRecognizer:tap];  }    #pragma mark - 代理方法  /**   *  当点击view的时候,会先调用这个方法   */  - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch  {      CGPoint pos = [touch locationInView:touch.view];      if (pos.x <= self.iconView.frame.size.width * 0.5) {          return YES;      }      return NO;  }    - (void)testTap  {      // 1.创建手势识别器对象      UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];      // 连续敲击2次,手势才能识别成功      tap.numberOfTapsRequired = 2;      tap.numberOfTouchesRequired = 2;        // 2.添加手势识别器对象到对应的view      [self.iconView addGestureRecognizer:tap];        // 3.添加监听方法(识别到了对应的手势,就会调用监听方法)      [tap addTarget:self action:@selector(tapView)];  }    - (void)tapView  {      NSLog(@"-----我敲击了屏幕！！");  }    @end

长按和轻扫实例

@interface GRViewController ()  @property (weak, nonatomic) IBOutlet UIView *redView;    @end    @implementation GRViewController    - (void)viewDidLoad  {      [super viewDidLoad];        UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeView)];        swipe.direction = UISwipeGestureRecognizerDirectionUp;        [self.redView addGestureRecognizer:swipe];  }    - (void)swipeView  {      NSLog(@"swipeView");  }    - (void)testLongPress  {      UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] init];      [longPress addTarget:self action:@selector(longPressView)];        // 至少长按2秒      longPress.minimumPressDuration = 2;        // 在触发手势之前,50px范围内长按有效      longPress.allowableMovement = 50;        [self.redView addGestureRecognizer:longPress];  }    - (void)longPressView  {      NSLog(@"长按了红色的view");  }    @end

缩放和旋转实例

@interface GRViewController () <UIGestureRecognizerDelegate>  @property (weak, nonatomic) IBOutlet UIImageView *iconView;  @end    @implementation GRViewController    - (void)viewDidLoad  {      [super viewDidLoad];        [self testPinchAndRotate];  }    #pragma mark - 手势识别器的代理方法    /**   *  是否允许多个手势识别器同时有效   *  Simultaneously : 同时地   */  - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer  {      return YES;  }    #pragma mark - 缩放 + 旋转  - (void)testPinchAndRotate  {      [self testPinch];      [self testRotate];  }    #pragma mark - 缩放手势(捏合手势)  - (void)testPinch  {      UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchView:)];      pinch.delegate = self;      [self.iconView addGestureRecognizer:pinch];  }    - (void)pinchView:(UIPinchGestureRecognizer *)pinch  {      pinch.view.transform = CGAffineTransformScale(pinch.view.transform, pinch.scale, pinch.scale);      pinch.scale = 1; // 这个真的很重要!!!!!  }    #pragma mark - 旋转手势  - (void)testRotate  {      UIRotationGestureRecognizer *recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotateView:)];      recognizer.delegate = self;      [self.iconView addGestureRecognizer:recognizer];  }    - (void)rotateView:(UIRotationGestureRecognizer *)recognizer  {      recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);      recognizer.rotation = 0; // 这个很重要!!!!!  }    @end

拖拽实例

@interface GRViewController ()  @property (weak, nonatomic) IBOutlet UIView *purpleView;    @end    @implementation GRViewController    - (void)viewDidLoad  {      [super viewDidLoad];        UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panView:)];      [self.purpleView addGestureRecognizer:pan];  }    - (void)panView:(UIPanGestureRecognizer *)pan  {        switch (pan.state) {          case UIGestureRecognizerStateBegan: // 开始触发手势                break;            case UIGestureRecognizerStateEnded: // 手势结束                break;            default:              break;      }        // 1.在view上面挪动的距离      CGPoint translation = [pan translationInView:pan.view];      CGPoint center = pan.view.center;      center.x += translation.x;      center.y += translation.y;      pan.view.center = center;        // 2.清空移动的距离      [pan setTranslation:CGPointZero inView:pan.view];  }    @end

手势识别的状态

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {      // 没有触摸事件发生，所有手势识别的默认状态      UIGestureRecognizerStatePossible,      // 一个手势已经开始但尚未改变或者完成时      UIGestureRecognizerStateBegan,      // 手势状态改变      UIGestureRecognizerStateChanged,      // 手势完成      UIGestureRecognizerStateEnded,      // 手势取消，恢复至Possible状态      UIGestureRecognizerStateCancelled,       // 手势失败，恢复至Possible状态      UIGestureRecognizerStateFailed,      // 识别到手势识别      UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded  };