ios对图像进行压缩源码

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{
CGSize imageSize = image.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;

if (width <= newSize.width && height <= newSize.height){
return image;
}

if (width == 0 || height == 0){
return image;
}

CGFloat widthFactor = newSize.width / width;
CGFloat heightFactor = newSize.height / height;
CGFloat scaleFactor = (widthFactor

CGSize targetSize = CGSizeMake(scaledWidth,scaledHeight);

UIGraphicsBeginImageContext(targetSize);
[image drawInRect:CGRectMake(0,0,scaledWidth,scaledHeight)];
UIGraphicsEndImageContext();
return newImage;

}