ios - UIlabel中的字符串如何对齐？

Question

有一个标签，它的宽度是 100，还有一些字符串，比如'ABC'，'ABCD'，'ABCDE'。我需要标签显示像'A B C'，'A B C D'这样的字符串， 'ABCDE'。该怎么做？

Answer 1

您可以使用 NSAttributedString 和 NSKernAttributeName 作为字母间距。我为您的目的创建了一个简单的子类:

class StretchingLabel: UILabel {

    override init(frame: CGRect) {
        super.init(frame: frame)
        sharedInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        sharedInit()
    }

    private func sharedInit() {
        self.lineBreakMode = .byClipping
        self.textAlignment = .center
    }

    override func awakeFromNib() {
        super.awakeFromNib()
        realignText()
    }

    private var scale: CGFloat { return UIScreen.main.scale }

    override var text: String? {
        didSet {
            realignText()
        }
    }

    private func realignText() {
        guard let text = text else { return }

        let textWidth = ceil((text as NSString).boundingRect(with: self.frame.size, options: [], attributes: [NSFontAttributeName: self.font], context: nil).width * scale) / scale
        let availableWidth = self.frame.width - textWidth
        let interLetterSpacing = availableWidth / CGFloat(text.characters.count - 1)

        let attributedText = NSAttributedString(string: text, attributes: [NSFontAttributeName: self.font, NSKernAttributeName: interLetterSpacing])
        self.attributedText = attributedText
    }

}