事件处理

触摸事件、手势、响应者链、运行循环。

 

（一）触摸事件

（1）在iOS中的事件可以分为三个类型，触摸事件，加速计事件（摇一摇，呵呵~），远程控制事件（耳机控制音量）。

（2）触摸事件：

     1.响应者对象：只要继承了UIResponder的对象就可以处理事件，称为响应者对象。UIApplication，UIViewController，UIView都继承UIResponder，所以都可以处理响应事件。

     2.UIResponder：

- (nullable UIResponder*)nextResponder;

 

// （能够）成为第一响应者

- (BOOL)canBecomeFirstResponder;    // default is NO
- (BOOL)becomeFirstResponder;

- (BOOL)canResignFirstResponder;    // default is YES
- (BOOL)resignFirstResponder;

- (BOOL)isFirstResponder;

 

 

// 手指触摸
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;
// 手指移动
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;
// 手指移开   —> 这三个是一个完整的响应事件
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;
// 手指取消  —> 非正常手指移开（突然接电话什么时候会调用）
- (void)touchesCancelled:(nullable NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event;

 

 

*这里所指的手指，都是一根或者多跟手指。touches里面放的都是UITouch对象，放到NSSet数组里面。

*5S以后手机是64位的了。这时候.count NSUInteger什么的就最好用zd%和tu%了。要不切换32位又会警告。

     3.UITouch对象

// 触摸时间
@property(nonatomic,readonly) NSTimeInterval      timestamp;
@property(nonatomic,readonly) UITouchPhase        phase;
@property(nonatomic,readonly) NSUInteger          tapCount;   // touch down within a certain point within a certain amount of time
@property(nonatomic,readonly) UITouchType        type NS_AVAILABLE_IOS(9_0);

// majorRadius and majorRadiusTolerance are in points
// The majorRadius will be accurate +/- the majorRadiusTolerance
@property(nonatomic,readonly) CGFloat majorRadius NS_AVAILABLE_IOS(8_0);
@property(nonatomic,readonly) CGFloat majorRadiusTolerance NS_AVAILABLE_IOS(8_0);

@property(nullable,nonatomic,readonly,strong) UIWindow                        *window;
@property(nullable,nonatomic,readonly,strong) UIView                          *view;
@property(nullable,nonatomic,readonly,copy)   NSArray <UIGestureRecognizer *> *gestureRecognizers NS_AVAILABLE_IOS(3_2);

- (CGPoint)locationInView:(nullable UIView *)view;
- (CGPoint)previousLocationInView:(nullable UIView *)view;

 

 

*tapCount很少用，一般用用于判断双击，双击一般用于放大图片。

*一个手指对应一个UITouch对象。保存着本次手指触摸相关的信息，比如位置，时间，阶段。俩手指就俩UITouch。手指移动时候会更新UITouch对象，手指离开就会销毁UITouch。

（二）单点触摸案例：

 1>手指在view上 view跟随    —> 子view touchBegin

 2>当手指点击view的时候 view的中心跑到手指的位置  —> 子view touchMoved

 3>手指再空白处 view跟随  —> 主view touchMoved

 4>手指再空白处 viewX值跟随   —> 主view touchMoved

 

子view：

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
   
   
    // 1.单击，子view变成中心
    UITouch *touch = touches.anyObject;
   
    // 获得现在的点
    CGPoint nowPoint = [touch locationInView:self.superview];

    self.center = nowPoint;
   

}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
   
    // 3.拖拽时候跟着鼠标走
    UITouch *touch = touches.anyObject;
    // 获得当前的点
    CGPoint previousPoint = [touch previousLocationInView:self.superview];
    // 获得现在的点
    CGPoint nowPoint = [touch locationInView:self.superview];
    NSLog(@"%@",NSStringFromCGPoint(nowPoint));
    NSLog(@"%@",NSStringFromCGPoint(previousPoint));
    // 获取x，y偏移量
    CGFloat x = nowPoint.x - previousPoint.x;
    CGFloat y = nowPoint.y - previousPoint.y;
    self.transform = CGAffineTransformTranslate(self.transform,x , y);
  
}
主view
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
   
    // 点击外面view时候，橘色view中心变变成点击点
    UITouch *touch = touches.anyObject;
    self.orangeView.center = [touch locationInView:self];
}
 

 

（三）多点触摸案例

1.多点触摸默认是不开启的。需要勾选。

2.代码：

// 单击一下随机出来一个颜色的图

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
   
    NSLog(@"%@",self.imageArray); // 这个是有的，好的.
   
   
    for (UITouch *t in touches) {
       
        CGPoint nowPoint = [t locationInView:self.superview];
       
        UIImageView *imgView = [[UIImageView alloc] initWithImage:[self ramdomImage]];
       
        imgView.center = nowPoint;
       
        [self addSubview:imgView];
       
        [UIView animateWithDuration:2.0 animations:^{
           
            imgView.alpha = 0;
           
        } completion:^(BOOL finished) {
            [imgView removeFromSuperview];
        }];
       
    }

}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
   
    for (UITouch *t in touches) {
       
        CGPoint nowPoint = [t locationInView:self.superview];
       
        UIImageView *imgView = [[UIImageView alloc] initWithImage:[self ramdomImage]];
       
        imgView.center = nowPoint;
       
        [self addSubview:imgView];
       
        [UIView animateWithDuration:2.0 animations:^{
           
            imgView.alpha = 0;
           
        } completion:^(BOOL finished) {
            [imgView removeFromSuperview];
        }];
       
    }
   
   
}


- (UIImage *)ramdomImage {
   
   
    UIImage *image = self.imageArray[arc4random() % self.imageArray.count];
   
    return image;
}


// 懒加载
- (NSArray *)imageArray {
   
    if (_imageArray == nil) {
       
        _imageArray = @[[UIImage imageNamed:@"spark_1"],[UIImage imageNamed:@"spark_2"],[UIImage imageNamed:@"spark_3"],[UIImage imageNamed:@"spark_4"],[UIImage imageNamed:@"spark_5"],[UIImage imageNamed:@"spark_6"],];
    }
    return  _imageArray;
   
}