浅析iOS给图片加水印的方法

+ (UIImage *)imageWithimage:(UIImage *)image content:(NSString *)content frame:(CGRect)frame;

+ (UIImage *)imageWithimage:(UIImage *)image content:(NSString *)content frame:(CGRect)frame {
 // 开启图形'上下文'
 UIGraphicsBeginImageContextWithOptions(image.size, NO, 0);
 // 绘制原生图片
 [image drawAtPoint:CGPointZero];
 // 在原生图上绘制文字
 NSString *str = content;
 // 创建文字属性字典
 NSDictionary *dictionary = @{NSForegroundColorAttributeName: [UIColor blackColor], NSFontAttributeName: [UIFont systemFontOfSize:20]};
 // 绘制文字属性
 [str drawInRect:frame withAttributes:dictionary];
 // 从当前上下文获取修改后的图片
 UIImage *imageNew = UIGraphicsGetImageFromCurrentImageContext();
 // 结束图形上下文
 UIGraphicsEndImageContext();
 return imageNew;
}

 double device = [[UIDevice currentDevice].systemVersion doubleValue];
 if (device >= 7.0f) {
  // do something
 }

 // 调用方法传入一个image对象,想要添加的文字和文字所在位置
 UIImage *image = [UIImage imageWithimage:[UIImage imageNamed:@"3"] content:@"伊利丹" frame:      CGRectMake(20, 500, 100, 100)];
 UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, kScreenWidth, kScreenHeight)];
 imageView.image = image;
 [self.view addSubview:imageView];