图片压缩

//图片大小缩放

+ (UIImage *) scaleImage:(UIImage *)image toSize:(CGSize)size {

    UIGraphicsBeginImageContext(size);          //size 为CGSize类型，即你所需要的图片尺寸

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

    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return scaledImage;   //返回的就是已经改变的图片

}

 //压缩图片,并返回成数据格式的

+ (NSData *) zipImage:(UIImage *)img rate:(CGFloat)rate{

    NSData *retImg = UIImageJPEGRepresentation(img, 0.5);

    if (retImg==nil) {

        retImg = UIImagePNGRepresentation(img);

    }

    return retImg;

} 

图片压缩

原文：http://www.cnblogs.com/TheYouth/p/4981349.html