有些时候经常需要对系统本有的类方法进行扩充，于是可能需要对类采用继承或者分类的方式来实现需要。

最近写的一个项目用到了一些对图片进行处理的一些扩充方法。

涉及到的方法:

比较常用的类似于拉伸图片，拼接图片名称或者以颜色生成图片等。

拼接图片名称：

+ (UIImage *)imageMatchSizeWithName:(NSString *)imageName
{
    if (__Device_Iphone_5__)       //iphone5,5s
    {
        NSString *ext = [imageName pathExtension];
        
        imageName = [imageName stringByDeletingPathExtension];
        imageName = [imageName stringByAppendingString:@"-568h@2x"];
        imageName = [imageName stringByAppendingPathExtension:ext];
    }
    
    return [UIImage imageNamed:imageName];
}

拉伸图片到指定尺寸：

+ (UIImage *)compressImage:(UIImage *)imgSrc toSize:(CGSize)size
{
    UIGraphicsBeginImageContext(size);
    CGRect rect = {{0,0}, size};
    [imgSrc drawInRect:rect];
    UIImage *compressedImg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return compressedImg;
}

指定位置获取像素点平铺拉伸图片

+ (UIImage *)strechImageWithName:(NSString *)imageName
{
    UIImage *image = [UIImage imageNamed:imageName];
    
    return [image stretchableImageWithLeftCapWidth:image.size.width*0.5 topCapHeight:image.size.height*0.5];
}

+ (UIImage *)strechImageWithName:(NSString *)imageName posX:(CGFloat)x posY:(CGFloat)y
{
    UIImage *image = [UIImage imageNamed:imageName];
    
    return [image stretchableImageWithLeftCapWidth:image.size.width*x topCapHeight:image.size.height*y];
}

截屏：

+ (UIImage *)screenshot
{
    CGSize imageSize = [[UIScreen mainScreen] bounds].size;
    
    if (NULL != UIGraphicsBeginImageContextWithOptions) {
        UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    } else {
        UIGraphicsBeginImageContext(imageSize);
    }
    
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    for (UIWindow *window in [[UIApplication sharedApplication] windows]) {
        if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen]) {
            CGContextSaveGState(context);
            
            CGContextTranslateCTM(context, [window center].x, [window center].y);
            
            CGContextConcatCTM(context, [window transform]);
            
            CGContextTranslateCTM(context,
                                  -[window bounds].size.width * [[window layer] anchorPoint].x,
                                  -[window bounds].size.height * [[window layer] anchorPoint].y);
            
            [[window layer] renderInContext:context];
            
            CGContextRestoreGState(context);
        }
    }
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return image;
}

增加水印：

+ (UIImage *)addImage:(UIImage *)image addMsakImage:(UIImage *)maskImage maskFrame:(CGRect)pos
{
    UIGraphicsBeginImageContext(image.size);
    [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
    
    //水印图片的位置
    [maskImage drawInRect:pos];
    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return resultingImage;
}

指定颜色生成图片：

+ (UIImage *)imageWithColor:(UIColor *)color
{
    CGRect rect = CGRectMake(0, 0, 1, 1);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

相对于上述方法，进行模糊稍微麻烦一些，也可以使用CoreImage中的高斯模糊滤镜，CoreImage的简单使用可以参照之前的博客：

CoreImage的使用及常见滤镜工具(一)

+ (UIImage *)blurImage:(UIImage *)src amount:(CGFloat)amount
{
    if (amount < 0.0 || amount > 1.0) {
        amount = 0.5;
    }
    
    int boxSize = (int)(amount * 40);
    boxSize = boxSize - (boxSize % 2) + 1;
    
    CGImageRef img = src.CGImage;
    
    vImage_Buffer inBuffer, outBuffer;
    vImage_Error error;
    
    void *pixelBuffer;
    
    CGDataProviderRef inProvider = CGImageGetDataProvider(img);
    CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
    
    inBuffer.width = CGImageGetWidth(img);
    inBuffer.height = CGImageGetHeight(img);
    inBuffer.rowBytes = CGImageGetBytesPerRow(img);
    
    inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);
    
    pixelBuffer = malloc(CGImageGetBytesPerRow(img) * CGImageGetHeight(img));
    
    outBuffer.data = pixelBuffer;
    outBuffer.width = CGImageGetWidth(img);
    outBuffer.height = CGImageGetHeight(img);
    outBuffer.rowBytes = CGImageGetBytesPerRow(img);
    
    error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
    
    if (!error) {
        error = vImageBoxConvolve_ARGB8888(&outBuffer, &inBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
        
        if (!error) {
            error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
        }
    }
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,
                                             outBuffer.width,
                                             outBuffer.height,
                                             8,
                                             outBuffer.rowBytes,
                                             colorSpace,
                                             (CGBitmapInfo)kCGImageAlphaNoneSkipLast);
    
    CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
    
    UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
    
    CGContextRelease(ctx);
    CGColorSpaceRelease(colorSpace);
    
    free(pixelBuffer);
    CFRelease(inBitmapData);
    
    CGColorSpaceRelease(colorSpace);
    CGImageRelease(imageRef);
    
    return returnImage;
}

实现即使不是太清楚，也可以直接拿来用就行。

资源位置

GitHub：UIImage-HR

CSDN：iOS图片分类

以上就是本篇博客全部内容，欢迎指正和交流。转载注明出处~

UIImage常用的分类