xcode从视图中删除一些子视图

Question

问候所有,

我是一个菜鸟,我一直在努力解决这个问题.

我通过UItouch将图像添加到视图中.视图包含一个背景,顶部将添加新图像.如何清除我从子视图添加的图像,而不删除作为背景的UIImage.非常感谢任何帮助.提前致谢.

这是代码:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *) event { 
NSUInteger numTaps = [[touches anyObject] tapCount];

if (numTaps==2) {
    imageCounter.text =@"two taps registered";      

//__ remove images  
    UIView* subview;
    while ((subview = [[self.view subviews] lastObject]) != nil)
        [subview removeFromSuperview];

    return;

}else {

    UITouch *touch = [touches anyObject];
    CGPoint touchPoint = [touch locationInView:self.view];
    CGRect myImageRect = CGRectMake((touchPoint.x -40), (touchPoint.y -45), 80.0f, 90.0f); 
    UIImageView *myImage = [[UIImageView alloc] initWithFrame:myImageRect];

    [myImage setImage:[UIImage imageNamed:@"pg6_dog_button.png"]];
     myImage.opaque = YES; // explicitly opaque for performance


    [self.view addSubview:myImage];
    [myImage release];

    [imagesArray addObject:myImage];

    NSNumber *arrayCount =[self.view.subviews count];
    viewArrayCount.text =[NSString stringWithFormat:@"%d",arrayCount];
    imageCount=imageCount++;
    imageCounter.text =[NSString stringWithFormat:@"%d",imageCount];

}

}

Answer 1

您需要的是一种区分添加的UIImageView对象与背景的方法UIImageView.我有两种方法可以做到这一点.

方法1:为添加的UIImageView对象分配特殊标记值

每个UIView对象都有一个tag属性,它只是一个整数值,可用于标识该视图.您可以将每个添加的视图的标记值设置为7,如下所示:

myImage.tag = 7;

然后,要删除添加的视图,您可以单步执行所有子视图,只删除标记值为7的子视图:

for (UIView *subview in [self.view subviews]) {
    if (subview.tag == 7) {
        [subview removeFromSuperview];
    }
}

方法2:记住背景视图

另一种方法是保留对背景视图的引用,以便将其与添加的视图区分开来.创建一个IBOutletfor background UIImageView并在Interface Builder中以通常的方式指定它.然后,在删除子视图之前,请确保它不是背景视图.

for (UIView *subview in [self.view subviews]) {
    if (subview != self.backgroundImageView) {
        [subview removeFromSuperview];
    }
}