Question

The following code draws some text over an image:

UIGraphicsBeginImageContext(image.size);
[image drawAtPoint:CGPointZero];

NSString *stamp = @"Internal Use Only";
[stamp drawAtPoint:CGPointMake(10, 10) withFont:[UIFont systemFontOfSize:32]];

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

If the code is executed again using a different string, both strings are combined and not legible. How can I make this so drawAtPoint() overlays the previous string?

Answer 1

I was able to make this work by rendering a UITextView. These know how to draw themselves via their layer property and can display multiple lines (added bonus!):

CGContextRef context = UIGraphicsGetCurrentContext();
NSString *stamp = @"Internal Use Only";
CGRect frame = CGRectMake(0, 0, 120, 80);
textview.frame = frame;
textview.text = stamp;
textview.font = [UIFont systemFontOfSize:32];
[textview.layer renderInContext:context];