Get height of UIView based on specific width before showing view

Question

I have a UIView which I have designed in Interface Builder. It basically consists out of a header image and some text (UILabel) below. The view is being shown modally with a custom Transition and doesn't fill the whole screen.

There is like a 20 pixels margin on the left and right and 40 px on the top. The UILabel gets filled with some text that's coming from the web. What I want do do, is to find (or should I say predict) the height of the whole view for a specific width. How can I do that?

Answer 1

You need to have both the picture and the label before calculating the aspected size. I guess you should use something like this (maybe adding the vertical inter-distance between the imageView and the Label to the sum, and maybe removing the lateral margins from the width):

objective C :

- (CGFloat)preferredHeightFromWidth:(CGFloat)width text:(NSString *)text font:(UIFont *)font image:(UIImage *)image
{
    // Calculate label height
    CGFloat labelHeight = [text
                           boundingRectWithSize:CGSizeMake(width, 10000)
                           options:NSStringDrawingUsesLineFragmentOrigin
                           attributes:@{NSFontAttributeName:font}
                           context:[[NSStringDrawingContext alloc] init]
                           ].size.height;

    // Calculate image height
    CGFloat ratio = image.size.height/ image.size.width;
    CGFloat imageHeight = (ratio * width);

    // Do the sum
    return labelHeight + imageHeight;
}

Swift:

func preferredHeight(width: CGFloat, text: NSString, font: UIFont, image: UIImage) -> CGFloat {
    // Calculate Label Height
    let labelRect = text.boundingRect(
        with: CGSize.init(width: width, height: 10000),
        options: .usesLineFragmentOrigin,
        attributes: [NSFontAttributeName : font],
        context: NSStringDrawingContext())
    let labelHeight = labelRect.height

    // Calculate Image Height
    let ratio = image.size.height / image.size.width
    let imageHeight = ratio / width

    // Calculate Total Height
    let height = labelHeight + imageHeight

    // Return Height Value
    return height
}

(Thanks to Christopher Hannah for swift version)