+ (instancetype)waterImageWithBg:(NSString *)bg logo:(NSString *)logo
{
UIImage *bgImage = [UIImage imageNamed:bg];
// 1.创建一个基于位图的上下文(开启一个基于位图的上下文)
UIGraphicsBeginImageContextWithOptions(bgImage.size, NO, 0.0);
// 2.画背景
[bgImage drawInRect:CGRectMake(0, 0, bgImage.size.width, bgImage.size.height)];
// 3.画右下角的水印
UIImage *waterImage = [UIImage imageNamed:logo];
CGFloat scale = 0.2;
CGFloat margin = 5;
CGFloat waterW = waterImage.size.width * scale;
CGFloat waterH = waterImage.size.height * scale;
CGFloat waterX = bgImage.size.width - waterW - margin;
CGFloat waterY = bgImage.size.height - waterH - margin;
[waterImage drawInRect:CGRectMake(waterX, waterY, waterW, waterH)];
// 4.从上下文中取得制作完毕的UIImage对象
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// 5.结束上下文
UIGraphicsEndImageContext();
return newImage;
}
UIImage创建水印的分类方法
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转载自invictus-fang.iteye.com/blog/2155190
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