CALayer renderInContext iOS7

问题

I'm rendering multiple layers to get one final image. One of the images contains a face, and another one contains a background with a transparent gradient around the face so that the real background is hidden. In iOS6 it works perfectly but it is creating a weird effect with the transparent gradient in iOS7.

The code:

CGRect rect = [[UIScreen mainScreen] bounds];
UIGraphicsBeginImageContext(rect.size);

CGContextRef context = UIGraphicsGetCurrentContext();

[faceImageView.layer renderInContext:context];
[fakeBackgroundImageView.layer renderInContext:context];

UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

The results in iOS6 and iOS7:

回答1:

Ok, the solution was changing this line:

UIGraphicsBeginImageContext(rect.size);

for this one:

UIGraphicsBeginImageContextWithOptions(rect.size, TRUE, [[UIScreen mainScreen] scale]);

Now it also works in iOS7

来源：https://stackoverflow.com/questions/19024785/calayer-renderincontext-ios7