如何使用NSKernAttribute快速將UILabel子類化並將字母間距設置為1.5

Question

我試圖對UILabel進行子類化，以便將其默認字距設置為1.5，然后在我的應用程序中將其與多個標簽一起使用。 目標是將默認字距設置為開箱即用，這樣我就可以避免在各處重復編寫代碼，同時將標簽設置為屬性文本和常規文本的混合示例：

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

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

這兩個標簽的核數均應為1.5

這是我到目前為止所擁有的

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

到目前為止，這是我的想法，如果有人想出更好的解決方案，我現在將使用此解決方案，我也很樂意嘗試

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viewController中這樣使用它

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)

我認為這可以減少為UILabel類的擴展，就像這樣

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
   }
}

Answer 2

這樣子類化UILabel怎么樣：

class TestKerningLabel: UILabel {
 func addKerning(kerningValue: Double) {
    let attributedString = self.attributedText as! NSMutableAttributedString
    attributedString.addAttribute(NSKernAttributeName, value: kerningValue, range: NSMakeRange(0, attributedString.length))
    self.attributedText = attributedString
 }
}

然后在您的VC中使用它：

let testLabel = TestKerningLabel()
testLabel.attributedText = NSAttributedString(string: "test")
testLabel.addKerning(kerningValue: 1.5)
view.addSubview(testLabel)