触摸 - 如何在到达某个 Y 点时停止 UIIMageView 移动

Question

我在屏幕底部有一个图像。

我希望用户向上移动图像直到它到达某个 Y 点，如下所示：

[door setCenter:CGPointMake(160,347)];

到目前为止，当您向上拖动图像（门）时，它会继续经过我的目标点，但当您松开时，它会弹回正确的位置。

如果用户的手指仍在向上滑动，如何在到达某个点时停止图像移动？它会在 if 语句中吗？

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    if (startPoint.y < 347) {
         // something in here ?????
    }
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *myTouch = [touches anyObject];
    startPoint = [myTouch locationInView:self.view];
    NSLog(@"position = %f and  %f",startPoint.x,startPoint.y);
    [door setCenter:CGPointMake(160, startPoint.y)];
}  

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    [door setCenter:CGPointMake(160,347)];
}

Answer 1

如何在touchesMoved 方法中设置它。比如，

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *myTouch = [touches anyObject];
    startPoint = [myTouch locationInView:self.view];
    NSLog(@"position = %f and  %f",startPoint.x,startPoint.y);
    if (startPoint.y < 347) { //or suitable condition to verify your case
        [door setCenter:CGPointMake(160, startPoint.y)]; //then only set the center
    } else 
    { 
       [door setCenter:CGPointMake(160,347); 
    } 
}