whatsapp-image-compression

- (UIImage *)compressImage:(UIImage *)image{
    float actualHeight = image.size.height;
    float actualWidth = image.size.width;
    float maxHeight = 600.0;
    float maxWidth = 800.0;
    float imgRatio = actualWidth/actualHeight;
    float maxRatio = maxWidth/maxHeight;
    float compressionQuality = 0.5;//50 percent compression
    
    if (actualHeight > maxHeight || actualWidth > maxWidth) {
        if(imgRatio < maxRatio){
            //adjust width according to maxHeight
            imgRatio = maxHeight / actualHeight;
            actualWidth = imgRatio * actualWidth;
            actualHeight = maxHeight;
        }
        else if(imgRatio > maxRatio){
            //adjust height according to maxWidth
            imgRatio = maxWidth / actualWidth;
            actualHeight = imgRatio * actualHeight;
            actualWidth = maxWidth;
        }else{
            actualHeight = maxHeight;
            actualWidth = maxWidth;
        }
    }
    
    CGRect rect = CGRectMake(0.0, 0.0, actualWidth, actualHeight);
    UIGraphicsBeginImageContext(rect.size);
    [image drawInRect:rect];
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    NSData *imageData = UIImageJPEGRepresentation(img, compressionQuality);
    UIGraphicsEndImageContext();

    return [UIImage imageWithData:imageData];
}

swift code

@IBAction func signUp(sender: AnyObject) {

    let imageData = UIImagePNGRepresentation(self.profilePic.image)

    let image = UIImage(data: imageData)

    func compressImage(image:UIImage) -> NSData {
        // Reducing file size to a 10th

        var actualHeight : CGFloat = image.size.height
        var actualWidth : CGFloat = image.size.width
        var maxHeight : CGFloat = 1136.0
        var maxWidth : CGFloat = 640.0
        var imgRatio : CGFloat = actualWidth/actualHeight
        var maxRatio : CGFloat = maxWidth/maxHeight
        var compressionQuality : CGFloat = 0.5

        if (actualHeight > maxHeight || actualWidth > maxWidth){
            if(imgRatio < maxRatio){
                //adjust width according to maxHeight
                imgRatio = maxHeight / actualHeight;
                actualWidth = imgRatio * actualWidth;
                actualHeight = maxHeight;
            }
            else if(imgRatio > maxRatio){
                //adjust height according to maxWidth
                imgRatio = maxWidth / actualWidth;
                actualHeight = imgRatio * actualHeight;
                actualWidth = maxWidth;
            }
            else{
                actualHeight = maxHeight;
                actualWidth = maxWidth;
                compressionQuality = 1;
            }
        }

        var rect = CGRectMake(0.0, 0.0, actualWidth, actualHeight);
        UIGraphicsBeginImageContext(rect.size);
        image.drawInRect(rect)
        var img = UIGraphicsGetImageFromCurrentImageContext();
        let imageData = UIImageJPEGRepresentation(img, compressionQuality);
        UIGraphicsEndImageContext();

        return imageData;
    }

    let compressedImage = compressImage(image!)

    let picture = PFFile(name: "image.png", data: compressedImage)

    PFUser.currentUser()!.setObject(picture, forKey: "profilePic")
    PFUser.currentUser()!.saveInBackgroundWithBlock {
        (success: Bool, error: NSError?) -> Void in
        if (success) {
            println("image has been saved")
        } else {
            println("image failed")
        }
    }
}