如何對齊UIlabel中的字符串？

Question

有一個標籤，它的寬度是100，還有一些字符串，如'ABC'，'ABCD'，'ABCDE'。我需要標籤顯示字符串' AB C'，'ABC D'，'ABCDE'。該怎麼辦？

Answer 1

您可以使用NSAttributedString和NSKernAttributeName作爲字母間距。我創建了供您使用簡單的子類：

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 
    } 

}