ios - 如何使用 NSKernAttribute 在字母间距设置为 1.5 的情况下快速子类化 UILabel

Question

我正在尝试对 UILabel 进行子类化，以便它的默认字距调整设置为 1.5然后我将在我的应用程序中使用它和多个标签。目标是开箱即用地设置默认内核，这样我就可以避免到处重复代码，标签也设置为属性文本和常规文本的混合示例:

@IBoutlet weak var myLabel: CustomeLabelWithKern!
myLabel.attributedText = myAttributedText

@IBOutlet weak var myOtherLabelInADifferentViewController: CustomeLabelWithKern!
myOtherLabelInADifferentViewController.text "Foo Bar"

这两个标签都应该有 1.5 的 kern

这是我目前所拥有的

class CustomLabel: UILabel {
   var kerning: CGFloat = 1.5

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

    private func setKerning(kern: CGFloat) {
        guard let text = self.text else { return }
        let range = NSRange(location: 0, length: text.characters.count)
        let mutableString = NSMutableAttributedString(attributedString: attributedText ?? NSAttributedString())
        mutableString.addAttribute(NSKernAttributeName, value: kern, range: range)
        attributedText = mutableString
    }
} 

Answer 1

这是我到目前为止所拥有的，我想我现在会使用这个解决方案，如果有人想出一个更好的解决方案，我也很乐意尝试一下

class CustomLabel: UILabel {
    static var kerning: CGFloat = 1.5

    override func awakeFromNib() {
       super.awakeFromNib()
       setKerning(CustomLabel.kerning)
    }

    func setKerning(kern: CGFloat) {
        let text = self.text ?? ""
        let range = NSRange(location: 0, length: text.characters.count)
        let mutableString = NSMutableAttributedString(attributedString: attributedText ?? NSAttributedString())
        mutableString.addAttribute(NSKernAttributeName, value: kern, range: range)
        attributedText = mutableString
    }
}

我可以在我的 viewController 中这样使用它

mylabel.text = "Hello World!" // this should be set to 1.5 by default but what if i am setting my label dynamically? 
mylabel.setKerning(1.5) // Here i am passing the value so if the label is set dynamically set it will have correct spacing 

// This also works if some of my labels have attributed text 
myAttibutedLabel.attributedText = myAttributedText
myAttributedLabel.setKerning(1.5)

我认为这可以简化为 UILabel 类的扩展像这样

extension UILabel {
    func setKerning(kern: CGFloat) {
        let text = self.text ?? ""
        let range = NSRange(location: 0, length: text.characters.count)
        let mutableString = NSMutableAttributedString(attributedString: attributedText ?? NSAttributedString())
        mutableString.addAttribute(NSKernAttributeName, value: kern, range: range)
        attributedText = mutableString
   }
}