CODEWITHSUNDEEP
ios
sv_lane
sv_lane

Reputation: 3087

CALayer renderInContext draws a blank image

This code works:

UIGraphicsBeginImageContextWithOptions(aRect.size, NO, 0.0);
[self.view drawViewHierarchyInRect:aRect afterScreenUpdates:YES];
anImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

but I need to support iOS 5 and 6. My Googling says this code ought to work:

UIGraphicsBeginImageContextWithOptions(aRect.size, NO, 0.0);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
anImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

but the image is blank. How do I take a snapshot of a view in iOS 5 and 6?

Upvotes: 0

Views: 3134

Answers (1)

sv_lane
sv_lane

Reputation: 3087

The solution was to scale the view to fit it the bounds of the graphics context. Most examples I found of this assume that the source view and the destination context are the same size. The graphics context I was using was much smaller than the view being snapshotted, and it was actually just clipping a corner of the view that was transparent.

UIGraphicsBeginImageContextWithOptions(aRect.size, NO, 0.0);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGFloat scale = CGRectGetWidth(aRect) / CGRectGetWidth(self.view.bounds);
CGContextScaleCTM(ctx, scale, scale);
[self.view.layer renderInContext:ctx];
anImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Upvotes: 4

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