iOS(五)触摸事件以及手势

在Cocoa中，代表触摸对象的类是UITouch，当用户触摸屏幕后，就会产生相应事件，触摸事件在屏幕上有一个周期，触摸开始，触摸点移动，触摸结束，中途取消

UITouch中还包含以下（CGPoint）locationInView:(UIView *)view,返回一个CGPoint类型的值，表示触摸点在view视图的位置，

（CGPoint）previousLocationInView：（UIView ＊）view，该方法记录了前一个坐标值

下面三个事件方法是手指触摸到屏幕就会触发的方法

//UITouch事件
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
NSLog(@"触摸开始");
if(event.allTouches.count==1)
for (UITouch *touch in event.allTouches) {
source =[touch locationInView:self.view];
}
}

-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
NSLog(@"moving");
}

-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
NSLog(@"触摸结束");
}
另一个事件触摸取消在类似触摸过程中突然来电打断就会触发

-(void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
NSLog(@"触摸cancel");
}

对于触摸在iOS开发中暂时还未遇到过，

但是手势接触的比较多，所以本次主要讲手势，手势主要分点击，放大缩小，向不同方向滑动

点击（涉及到几根手指，几次点击屏幕）

UITapGestureRecognizer *finger=[[UITapGestureRecognizer alloc]init];
[finger setNumberOfTouchesRequired:n];//设置需要n个手指才能触发

[finger setNumberOfTapsRequired:n];//设置需要触碰n下
// 手势触发条件
[finger addTarget:self action:@selector(finger)];
// 添加手势
[self.view addGestureRecognizer:finger];

两个手指放大or缩小（当进行放大缩小时，会返回一个scale值，>1是放大 <1是缩小，图片的放大缩小就是基于这个手势）

//放大缩小手势
    UIPinchGestureRecognizer *pinch=[[UIPinchGestureRecognizer alloc]init];
    [pinch addTarget:self action:@selector(pinch:)];
    [self.view addGestureRecognizer:pinch];

判断是放大还是缩小

-(void)pinch:(UIPinchGestureRecognizer *)pinch{
    if(pinch.scale>1){
    NSLog(@"拉大");
    label.text=@"拉大";
    }
    else{
    NSLog(@"缩小");
    label.text=@"缩小";
    }
}

向不同方向滑动的手势

//滑动手势向上
    UISwipeGestureRecognizer *swipeup=[[UISwipeGestureRecognizer alloc]init];
    [swipeup setDirection:UISwipeGestureRecognizerDirectionUp];
    [swipeup addTarget:self action:@selector(swipeup:)];
    [self.view addGestureRecognizer:swipeup];

<span style="font-size:14px;">-(void)swipeup:(UISwipeGestureRecognizer *)swipe{
    CGPoint point=[swipe locationInView:[self view]];
    
    label.text=[NSString stringWithFormat:@"向上滑动:%f,%f",point.x,point.y];
    if(swipe.state==UIGestureRecognizerStateBegan){
        source=[swipe locationInView:self.view];
    }
    else if(swipe.state==UIGestureRecognizerStateEnded){
        distance=[swipe locationInView:self.view];
        float juli;
        CGFloat x=(source.x-distance.x);
        CGFloat y=(source.y-distance.y);
        juli=sqrt((x*x)+(y*y));
        NSLog(@"%f",juli);
        dislabel.text=[NSString stringWithFormat:@"单指滑动距离:%f",juli];
    }
}</span>

虽然比较基础，但其实iOS很多复杂的都是基于基础