图像压缩

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- (UIImage*)scaleFromImage:(UIImage*)image scaledToSize :(CGSize)newSize { 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<heightFactor?widthFactor:heightFactor); CGFloat scaledWidth = width * scaleFactor; CGFloat scaledHeight = height * scaleFactor; CGSize targetSize = CGSizeMake(scaledWidth,scaledHeight); UIGraphicsBeginImageContext(targetSize); [image drawInRect :CGRectMake( 0 , 0 ,scaledWidth,scaledHeight)]; UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newImage; }