我有一个 UIView，我对其应用了图层蒙版。它适用于除视网膜 iPad 之外的所有设备。在视网膜 iPad 上，被遮盖的视图不显示。如果我取下遮罩，视图会显示在视网膜 iPad 上。
面具很简单。它显示了整个视图，除了从底部边缘取出的小三角形。
contentView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [[UIScreen mainScreen] applicationFrame].size.width, [[UIScreen mainScreen] applicationFrame].size.height - 50.0)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
CGMutablePathRef path = CGPathCreateMutable();
float triangleDepth = 10;
CGPathMoveToPoint(path, NULL, 0, 0);
CGPathAddLineToPoint(path, NULL, contentView.frame.size.width, 0);
CGPathAddLineToPoint(path, NULL, contentView.frame.size.width, contentView.frame.size.height);
CGPathAddLineToPoint(path, NULL, (contentView.frame.size.width / 2.0) + triangleDepth, contentView.frame.size.height);
CGPathAddLineToPoint(path, NULL, (contentView.frame.size.width / 2.0), contentView.frame.size.height - triangleDepth);
CGPathAddLineToPoint(path, NULL, (contentView.frame.size.width / 2.0) - triangleDepth, contentView.frame.size.height);
CGPathAddLineToPoint(path, NULL, 0, contentView.frame.size.height);
CGPathCloseSubpath(path);
[maskLayer setPath:path];
CGPathRelease(path);
contentView.layer.mask = maskLayer;
contentView.clipsToBounds = NO;
[self.view addSubview:contentView];
这段代码适用于每台设备，那么视网膜 iPad 有什么不同会阻止它工作呢？