图片加水印的多种方式

1.加文字
- (UIImage *)imageWithLogoText:(UIImage *)img text:(NSString *)text1 
{      
    /////注：此为后来更改，用于显示中文。zyq,2013-5-8 
    CGSize size = CGSizeMake(200, img.size.height);          //设置上下文（画布）大小 
    UIGraphicsBeginImageContext(size);                       //创建一个基于位图的上下文(context)，并将其设置为当前上下文 
    CGContextRef contextRef = UIGraphicsGetCurrentContext(); //获取当前上下文 
    CGContextTranslateCTM(contextRef, 0, img.size.height);   //画布的高度 
    CGContextScaleCTM(contextRef, 1.0, -1.0);                //画布翻转 
    CGContextDrawImage(contextRef, CGRectMake(0, 0, img.size.width, img.size.height), [img CGImage]);  //在上下文种画当前图片 
     
    [[UIColor redColor] set];                                //上下文种的文字属性 
    CGContextTranslateCTM(contextRef, 0, img.size.height); 
    CGContextScaleCTM(contextRef, 1.0, -1.0); 
    UIFont *font = [UIFont boldSystemFontOfSize:16]; 
    [text1 drawInRect:CGRectMake(0, 0, 200, 80) withFont:font];       //此处设置文字显示的位置 
    UIImage *targetimg =UIGraphicsGetImageFromCurrentImageContext();  //从当前上下文种获取图片 
    UIGraphicsEndImageContext();                            //移除栈顶的基于当前位图的图形上下文。 
    return targetimg; 
     
     
    //注：此为原来，不能显示中文。无用。 
    //get image width and height 
    int w = img.size.width; 
    int h = img.size.height; 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    //create a graphic context with CGBitmapContextCreate 
    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst); 
    CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage); 
    CGContextSetRGBFillColor(context, 0.0, 1.0, 1.0, 1); 
    char* text = (char *)[text1 cStringUsingEncoding:NSUnicodeStringEncoding]; 
    CGContextSelectFont(context, "Georgia", 30, kCGEncodingMacRoman); 
    CGContextSetTextDrawingMode(context, kCGTextFill); 
    CGContextSetRGBFillColor(context, 255, 0, 0, 1); 
    CGContextShowTextAtPoint(context, w/2-strlen(text)*5, h/2, text, strlen(text)); 
    //Create image ref from the context 
    CGImageRef imageMasked = CGBitmapContextCreateImage(context); 
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 
    return [UIImage imageWithCGImage:imageMasked]; 
     
} 

2.新的添加文字水印的方法
#pragma mark -也是文字水印 
- (UIImage *) imageWithStringWaterMark:(NSString *)markString inRect:(CGRect)rect color:(UIColor *)color font:(UIFont *)font 
{ 
#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)]; 
     
    //文字颜色 
    [color set]; 
     
    //水印文字 
    [markString drawInRect:rect withFont:font]; 
     
    UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
     
    return newPic; 
} 

3.还是添加文字水印方法二
#pragma mark -还是文字水印 
- (UIImage *) imageWithStringWaterMark:(NSString *)markString atPoint:(CGPoint)point color:(UIColor *)color font:(UIFont *)font 
{ 
#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)]; 
     
    //文字颜色 
    [color set]; 
     
    //水印文字 
    [markString drawAtPoint:point withFont:font]; 
     
    UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
     
    return newPic; 
} 

4,加图片
#pragma mark - 加图片水印 
-(UIImage *)imageWithLogoImage:(UIImage *)img logo:(UIImage *)logo 
{ 
    //get image width and height 
    int w = img.size.width; 
    int h = img.size.height; 
    int logoWidth = logo.size.width; 
    int logoHeight = logo.size.height; 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    //create a graphic context with CGBitmapContextCreate 
    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst); 
    CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage); 
    CGContextDrawImage(context, CGRectMake(w-logoWidth, 0, logoWidth, logoHeight), [logo CGImage]); 
    CGImageRef imageMasked = CGBitmapContextCreateImage(context); 
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 
    return [UIImage imageWithCGImage:imageMasked]; 
    //  CGContextDrawImage(contextRef, CGRectMake(100, 50, 200, 80), [smallImg CGImage]); 
} 

5.新的添加图片水印的方法
#pragma mark -还是图片水印 
- (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; 
} 

6。加半透明的水印
//加半透明的水印 
-(UIImage *)imageWithTransImage:(UIImage *)useImage addtransparentImage:(UIImage *)transparentimg 
{ 
    UIGraphicsBeginImageContext(useImage.size); 
    [useImage drawInRect:CGRectMake(0, 0, useImage.size.width, useImage.size.height)]; 
    [transparentimg drawInRect:CGRectMake(0, useImage.size.height-transparentimg.size.height, transparentimg.size.width, transparentimg.size.height) blendMode:kCGBlendModeOverlay alpha:0.4f]; 
     
    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
    return resultingImage; 
}

参考链接