iPhone开发: How to create colored or translucent background for UIActionSheet?

Question

当您尝试在 iPhone 的“便笺”应用程序中删除便笺时，会弹出 UIActionSheet。该片材是半透明的(但不是黑色半透明的)。这是如何实现的？是否可以将UIActionSheet的背景设置为某种颜色？

Answer 1

我通常实现以下委托(delegate)方法:

- (void)willPresentActionSheet:(UIActionSheet *)actionSheet

只是为了制作一个样本。在本例中，我使用拉伸(stretch)的 png 作为背景:

- (void)willPresentActionSheet:(UIActionSheet *)actionSheet {
    UIImage *theImage = [UIImage imageNamed:@"detail_menu_bg.png"];    
    theImage = [theImage stretchableImageWithLeftCapWidth:32 topCapHeight:32];
    CGSize theSize = actionSheet.frame.size;
    // draw the background image and replace layer content  
    UIGraphicsBeginImageContext(theSize);    
    [theImage drawInRect:CGRectMake(0, 0, theSize.width, theSize.height)];    
    theImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    [[actionSheet layer] setContents:(id)theImage.CGImage];
}

这是结果: alt text http://grab.by/4yF1