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 
};


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