ios 给图片添加水印

//第一种添加水印方法

-(UIImage *)watermarkImage:(UIImage *)img withName:(NSString *)name{
   NSString* mark = name;
   int w = img.size.width;
   int h = img.size.height;

   UIGraphicsBeginImageContext(img.size);
   [img drawInRect:CGRectMake(, , w, h)];

   NSDictionary *attr = @{
              NSFontAttributeName: [UIFont boldSystemFontOfSize:],//设置字体
                NSForegroundColorAttributeName : [UIColor redColor] //设置字体颜色
              };
   [mark drawInRect:CGRectMake(, , , ) withAttributes:attr];//左上角
   [mark drawInRect:CGRectMake(w - , , , ) withAttributes:attr];      //右上角
   [mark drawInRect:CGRectMake(w - , h - - , , ) withAttributes:attr];  //右下角
   [mark drawInRect:CGRectMake(, h - - , , ) withAttributes:attr];    //左下角
   UIImage *aimg = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   return aimg;
}

//第二种 画水印方法

- (UIImage *) imageWithWaterMask:(UIImage*)mask inRect:(CGRect)rect

{

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000

 if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0)

 {

 UIGraphicsBeginImageContextWithOptions([self size], NO, 0.0); // 0.0 for scale means "scale for device‘s main screen".

 }

#else

 if ([[[UIDevice currentDevice] systemVersion] floatValue] < 4.0)

 {

 UIGraphicsBeginImageContext([self size]);

 }

#endif

 //原图

 [self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];

 //水印图

 [mask drawInRect:rect];

 UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();

 UIGraphicsEndImageContext();

 return newPic;

}