我使用此代码向位于另一个视图上方的视图添加阴影。
CGRect rect = CGRectMake(90, 0, 230, 460);
FeedsViewController *feedsViewController = [[FeedsViewController alloc] init];
[feedsViewController.view setFrame:rect];
self.feedsViewController = feedsViewController;
[feedsViewController release];
[[feedsViewController.view layer] setShadowOffset:CGSizeMake(0, 1)];
[[feedsViewController.view layer] setShadowColor:[[UIColor darkGrayColor] CGColor]];
[[feedsViewController.view layer] setShadowRadius:3.0];
[[feedsViewController.view layer] setShadowOpacity:0.8];
[self.view.superview addSubview:feedsViewController.view];
但它不起作用,为什么?