Find the number of characters that fits in a UITextView with constant width and height with a given string?

Question

In my application I need to set Read more into the text view if text input is large.so my approach is to find the range of string that would fit in the text view and append

Answer 1

A rough swift translation of kgaidis's excellent answer.

extension UILabel {

    func numberOfCharactersThatFitLabel() -> Int {
        let fontRef = CTFontCreateWithName(self.font.fontName as CFStringRef, self.font.pointSize, nil)
        let attributes = NSDictionary(dictionary: [kCTFontAttributeName : fontRef])
        let attributeString = NSAttributedString(string: text!, attributes: attributes as? [String : AnyObject])
        let frameSetterRef = CTFramesetterCreateWithAttributedString(attributeString as CFAttributedStringRef)

        var characterFitRange:CFRange

        CTFramesetterSuggestFrameSizeWithConstraints(frameSetterRef, CFRangeMake(0, 0), nil, CGSizeMake(bounds.size.width, CGFloat(numberOfLines)*font.lineHeight), &characterFitRange)

        return characterFitRange.length
    }
}