这只是另一种绘制文本图像的方法来掩盖某些东西。它基于kCGBlendModeSourceIn
混合模式:您在清晰的背景上绘制文本,然后在整个地方绘制填充。
NSString *theString = ...;
UIFont *theFont = ...;
CGSize stringSize = [theString sizeWithFont:theFont];
// The background must be clear (fully transparent), hence NO as the 2nd argument
UIGraphicsBeginImageContextWithOptions(stringSize, NO, 0);
[theString drawAtPoint:CGPointZero withFont:theFont];
// This effectively colorizes the image. Use a pattern color...
[patternColor set];
UIRectFillUsingBlendMode(CGRectMake(0, 0, stringSize.width, stringSize.height), kCGBlendModeSourceIn);
// ... or an image:
[patternImage drawInRect:CGRectMake(0, 0, stringSize.width, stringSize.height) blendMode:kCGBlendModeSourceIn alpha:1.0f];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();