Resize UIImageView based on the size of the screen

ResizeUIImageViewForScreenSize

// From http://stackoverflow.com/questions/12648129/uiimageview-programmilly-manage-for-iphone5-and-iphone4/12774544#12774544

[self resizeImageView:self.backgroundImageView intoFrame:self.view.frame];

- (void)resizeImageView:(UIImageView *)imageView intoFrame:(CGRect)frame {
    // resizing is not needed if the height is already the same
    if (frame.size.height == imageView.frame.size.height) {
        return;
    }

    CGFloat delta = frame.size.height / imageView.frame.size.height;
    CGFloat newWidth = imageView.frame.size.width * delta;
    CGFloat newHeight = imageView.frame.size.height * delta;
    CGSize newSize = CGSizeMake(newWidth, newHeight);
    CGFloat newX = (imageView.frame.size.width - newWidth) / 2; // recenter image with broader width
    CGRect imageViewFrame = imageView.frame;
    imageViewFrame.size.width = newWidth;
    imageViewFrame.size.height = newHeight;
    imageViewFrame.origin.x = newX;
    imageView.frame = imageViewFrame;

    // now resize the image
    assert(imageView.image != nil);
    imageView.image = [self imageWithImage:imageView.image scaledToSize:newSize];
}

- (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}