UITouch触摸操作

1. 触摸操作的生命周期

• 手指触摸屏幕的瞬间
  在这个过程中，可以通过 touch.tapCount 判断是单击还是双击。
  可以通过 [touch locationInView:self.view] 来获取点击位置坐标

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #d12f1b}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}span.s1 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures}span.s3 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s4 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s5 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s6 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s7 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures}span.s8 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #000000}span.s9 {font-variant-ligatures: no-common-ligatures; color: #272ad8}span.s10 {font-variant-ligatures: no-common-ligatures; color: #d12f1b}span.s11 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures; color: #d12f1b}span.s12 {font-variant-ligatures: no-common-ligatures; color: #4f8187}

//当点击屏幕开始的瞬间，调用此函数，即状态1
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"手指触碰瞬间");
    //获取点击对象。anyObeject获取任何一个点击对象
    //一般只有一个点击对象
    UITouch* touch=[touches anyObject];
    
    
    //记录点击的次数
    
    if(touch.tapCount==1)
        NSLog(@"单次点击");
    else if (touch.tapCount==2)
        NSLog(@"双击");
    
}

• 手指在屏幕上未离开过程
  在这个过程中可以通过 [touch locationInView: ]来获取手指相对于当前视图的坐标。

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #d12f1b}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s3 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s4 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #000000}span.s5 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s6 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s7 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"手指在屏幕上, 并且移动。可以获取坐标数据");
    
    //获取手指相对当前视图的坐标
    UITouch* touch=[touches anyObject];
    CGPoint pt=[touch locationInView:self.view];

• 手指离开屏幕的瞬间

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #d12f1b}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s3 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s4 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s5 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s6 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"手指离开屏幕");
}

• 还有一个特殊情况下终止触屏操作的协议，比如游戏过程中来电话

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #d12f1b}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s3 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s4 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s5 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s6 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures}

-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"特殊情况下终端触屏.比如电话");
}

2.实现手指拖拽控制图片移动的功能

手指移动的偏移量决定图片移动的向量，所以需要计算此时手指坐标和上一时刻手指坐标的差值。

在ViewController.h中声明一个CGPoint，用来存放上一时刻手指位置：

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}span.s1 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s2 {font-variant-ligatures: no-common-ligatures}

CGPoint _mPtList;

然后获得此时手指位置并计算偏移量大小：
注意 计算完要把此时的位置赋给 _mPtList

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #4f8187}span.s1 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #000000}span.s2 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s3 {font-variant-ligatures: no-common-ligatures}span.s4 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s5 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s6 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s7 {font-variant-ligatures: no-common-ligatures; color: #4f8187}span.s8 {font-variant-ligatures: no-common-ligatures; color: #000000}

    //获取手指相对当前视图的坐标
    UITouch* touch=[touches anyObject];
    CGPoint pt=[touch locationInView:self.view];
    
    //每次移动偏移量大小
    float xOffset=pt.x-_mPtList.x;
    float yOffset=pt.y-_mPtList.y;
    
    _mPtList=pt;

然后根据偏移量改变图像视图的位置：

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s3 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s4 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s5 {font-variant-ligatures: no-common-ligatures; color: #272ad8}span.s6 {font-variant-ligatures: no-common-ligatures; color: #d12f1b}

    UIImageView* iView=[self.view viewWithTag:101];
    
    NSLog(@"x=%f,y=%f",pt.x,pt.y);
    
    iView.frame=CGRectMake(iView.frame.origin.x+xOffset, iView.frame.origin.y+yOffset, iView.frame.size.width, iView.frame.size.height);