ios - 绘制前如何清除 subview 的内容

Question

我使用两个 block 在我的 subview 上动态绘制一些按钮。一个计算纵向模式的帧数，另一个计算横向模式的帧数。它运作良好，但当我旋转时，它会覆盖旧的。因此，我的一些按钮来了两次。这是我检测方向的代码:

//i have defined blocks in viewDidLoad: and everything is ok till here
    - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
    {
        if(interfaceOrientation == UIInterfaceOrientationPortrait || interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown)
        {
            dispatch_async(dispatch_get_main_queue(), PortraitBlock);        
        }       
        else 
        { 
            dispatch_async(dispatch_get_main_queue(), LandscapeBlock);
               }
        return (interfaceOrientation == UIInterfaceOrientationLandscapeRight || 
                interfaceOrientation == UIInterfaceOrientationPortrait || 
                interfaceOrientation == UIInterfaceOrientationLandscapeLeft ||
                interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown);
    }

现在，我如何清理添加按钮的 View ？

注意:我在 UIView 对象上添加按钮，该对象也在 UIScrollView 对象上

Answer 1

hi,.,

Try below code with this all your button which you alloc on the view will be remove.

for(UIButton *view in yourview.subviews)
    {
        [view removeFromSuperview];
    }