在 TouchesBegan 上更改图像

Question

嘿，我试图在用户触摸 ImageView 时更改图像。目前 ImageView 具有图像“heart1.png”，因此当我触摸屏幕上的 ImageViewer 时，它将更改为“heart2.png”，这是我的代码，非常感谢帮助：

-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint location = [touch locationInView:self.view];
    if (location.x >= imageView.frame.origin.x && location.x <= imageView.frame.origin.x + imageView.frame.size.height && location.y >= imageView.frame.origin.y && location.y <= imageView.frame.origin.y + imageView.frame.size.height) {
        imageView.image = [UIImage imageNamed:@"heart2.png"];
    }    
}

Answer 1

这对我来说似乎是个问题：

if (location.x >= imageView.frame.origin.x && location.x <= imageView.frame.origin.x + imageView.frame.size. --> 高度 <--

可能应该是宽度:)

Answer 2

与其胡乱检查边界矩形的坐标，为什么不通过使用界面构建在图像上放置一个自定义（即不可见）UIButton 来简化事情呢？然后，您可以将 touchesUpInside 连接到 IBAction 方法。这样你的代码中就不会出现尴尬的 if 语句，并且犯这样的错误的可能性也会减少。

Answer 3

考虑使用 UIButton 代替。

[button setImage:[UIImage imageNamed:@"heart1.png"] forState:UIControlStateNormal];
[button setImage:[UIImage imageNamed:@"heart2.png"] forState:UIControlStateHighlighted];

Answer 4

不需要找到view的位置，也不需要移动UIImageView。只需这样做：

-(void)viewDidLoad 
{
    // imageView is your UIImageView
    imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0.0, 0.0, 320.0, 480.0)];
    [imageView setImage:[UIImage imageNamed:@"heart1.png"]];
    [imageView setUserInteractionEnabled:YES];

    // Make sure userInteractionEnable is set to be YES; otherwise the touch event will be happen on UIView not on ImageView;
   [self.view addSubview:imageView];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
    UITouch *touch = [[event allTouches]anyObject];
    if([touch view]==imageView)
        [imageView setImage:[UIImage imageNamed:@"heart2.png"]];
}