Figure out size of UILabel based on String in Swift

Question

I am trying to calculate the height of a UILabel based on different String lengths.

func calculateContentHeight() -> CGFloat{
    var maxLabelSize: CGSize         


        

Answer 1

I found that the accepted answer worked for a fixed width, but not a fixed height. For a fixed height, it would just increase the width to fit everything on one line, unless there was a line break in the text.

The width function calls the height function multiple times, but it is a quick calculation and I didn't notice performance issues using the function in the rows of a UITable.

extension String {

    public func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [.font : font], context: nil)

        return ceil(boundingBox.height)
    }

    public func width(withConstrainedHeight height: CGFloat, font: UIFont, minimumTextWrapWidth:CGFloat) -> CGFloat {

        var textWidth:CGFloat = minimumTextWrapWidth
        let incrementWidth:CGFloat = minimumTextWrapWidth * 0.1
        var textHeight:CGFloat = self.height(withConstrainedWidth: textWidth, font: font)

        //Increase width by 10% of minimumTextWrapWidth until minimum width found that makes the text fit within the specified height
        while textHeight > height {
            textWidth += incrementWidth
            textHeight = self.height(withConstrainedWidth: textWidth, font: font)
        }
        return ceil(textWidth)
    }
}