iOS UIImage dimension change not working

I am resizing a UIImage by changing the dimension. But it shows different dimension. For iPhone 6, I choose 1.25 time than the screen dimension which should come 937*1667. But after completing my resize operation is becomes 938*1251. I need it in declared dimension.

My code is :

    NSData *imageData;
    imageData=[[NSData alloc] initWithData:UIImageJPEGRepresentation((image), 1.0)];

    CGSize sz;
    sz.width=((isIphone4||isIphone5)?320*2.3:iPhone6?750*1.25:414*1.8);
    sz.height=((isIphone4||isIphone5)?568*2.3:iPhone6?667*1.25:768*1.8);

    if([imageData length]/1024>400)
        image=[self resizeImage:image scaledToSize:sz];

 //function call

-(UIImage *)resizeImage:(UIImage *)image scaledToSize:(CGSize)targetSize
{
   float actualHeight = image.size.height;
   float actualWidth = image.size.width;
   float maxHeight = targetSize.height;
   float maxWidth = targetSize.width;
   float imgRatio = actualWidth/actualHeight;
   float maxRatio = maxWidth/maxHeight;
   float compressionQuality = 0.50;//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];

}

What could be solution for possible solution ?