How to tell when a UILabel will be truncated an/or its line break position will change

Question

I have a multi-line UILabel (numberOfLines = 0). It\'s width can change at runtime, and sometimes this leads to truncation and/or re-wrapping. Some

Answer 1

Swift 3 solution

You can count the number of lines after assigning the string and compare to the max number of lines of the label.

import Foundation
import UIKit

extension UILabel {

    func countLabelLines() -> Int {
        // Call self.layoutIfNeeded() if your view is uses auto layout
        let myText = self.text! as NSString
        let attributes = [NSFontAttributeName : self.font]

        let labelSize = myText.boundingRect(with: CGSize(width: self.bounds.width, height: CGFloat.greatestFiniteMagnitude), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: attributes, context: nil)
        return Int(ceil(CGFloat(labelSize.height) / self.font.lineHeight))
    }

    func isTruncated() -> Bool {

        if (self.countLabelLines() > self.numberOfLines) {
            return true
        }
        return false
    }
}