如何将 NSNumberFormatter 与 AttributedString 一起使用？

Question

我找不到任何适用于在 NSTextField 和 NumberFormatter 中使用属性文本的主题。我想要完成的非常简单。我想在带有属性文本的可编辑NSTextField 上使用NumberFormatter，并保留文本属性。

目前，我已将NSTextFieldCell 子类化并实现它：

class AdjustTextFieldCell: NSTextFieldCell {

  required init(coder: NSCoder) {
    super.init(coder: coder)
    let attributes = makeAttributes()
    allowsEditingTextAttributes = true
    attributedStringValue = AttributedString(string: stringValue, attributes: attributes)
    //formatter = TwoDigitFormatter()
  }

  func makeAttributes() -> [String: AnyObject] {
    let style = NSMutableParagraphStyle()
    style.minimumLineHeight = 100
    style.maximumLineHeight = 100
    style.paragraphSpacingBefore = 0
    style.paragraphSpacing = 0
    style.alignment = .center
    style.lineHeightMultiple = 1.0
    style.lineBreakMode = .byTruncatingTail
    let droidSansMono = NSFont(name: "DroidSansMono", size: 70)!
    return [NSParagraphStyleAttributeName: style, NSFontAttributeName: droidSansMono, NSBaselineOffsetAttributeName: -60]
  }


}

此实现调整 NSTextField 实例中的文本以具有显示的属性。当我取消注释设置 formatter 属性的行时，NSTextField 将失去其属性。我的NumberFormatter如下：

class TwoDigitFormatter: NumberFormatter {

  override init() {
    super.init()
    let customAttribs = makeAttributes()
    textAttributesForNegativeValues = customAttribs.attribs
    textAttributesForPositiveValues = customAttribs.attribs
    textAttributesForZero = customAttribs.attribs
    textAttributesForNil = customAttribs.attribs
  }

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

  let maxLength = 2
  let wrongCharacterSet = CharacterSet(charactersIn: "0123456789").inverted

  override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
    if partialString.characters.count > maxLength {
      return false
    }

    if partialString.rangeOfCharacter(from: wrongCharacterSet) != nil {
      return false
    }

    return true
  }

  override func attributedString(for obj: AnyObject, withDefaultAttributes attrs: [String : AnyObject]? = [:]) -> AttributedString? {
    let stringVal = string(for: obj)

    guard let string = stringVal else { return nil }
    let customAttribs = makeAttributes()
    var attributes = attrs
    attributes?[NSFontAttributeName] = customAttribs.font
    attributes?[NSParagraphStyleAttributeName] = customAttribs.style
    attributes?[NSBaselineOffsetAttributeName] = customAttribs.baselineOffset

    return AttributedString(string: string, attributes: attributes)

  }

  func makeAttributes() -> (font: NSFont, style: NSMutableParagraphStyle, baselineOffset: CGFloat, attribs: [String: AnyObject]) {
    let style = NSMutableParagraphStyle()
    style.minimumLineHeight = 100
    style.maximumLineHeight = 100
    style.paragraphSpacingBefore = 0
    style.paragraphSpacing = 0
    style.alignment = .center
    style.lineHeightMultiple = 1.0
    style.lineBreakMode = .byTruncatingTail
    let droidSansMono = NSFont(name: "DroidSansMono", size: 70)!
    return (droidSansMono, style, -60, [NSParagraphStyleAttributeName: style, NSFontAttributeName: droidSansMono, NSBaselineOffsetAttributeName: -60])
  }
}

你可以从上面的代码中看到我已经尝试过：

1. 设置textAttributesFor... 属性。
2. 覆盖attributedString(for obj: AnyObject, withDefaultAttributes attrs: [String : AnyObject]? = [:])

我已经分别尝试了这两种解决方案，也分别尝试过，但都没有成功。

TLDR：
是否可以同时使用属性文本和NumberFormatter？如果是这样，怎么做？如果没有，我如何将带有属性文本的NSTextField 限制为仅数字和两个字符而不使用NumberFormatter？

Answer 1

对于将来想要实现行为的任何人，我可以通过子类化 NSTextView 并基本上像这样伪造 NSTextField 来做到这一点：

class FakeTextField: NSTextView {

  required init?(coder: NSCoder) {
    super.init(coder: coder)

    delegate = self

    let droidSansMono = NSFont(name: "DroidSansMono", size: 70)!
    configure(lineHeight: frame.size.height, alignment: .center, font: droidSansMono)
  }

  func configure(lineHeight: CGFloat, alignment: NSTextAlignment, font: NSFont) {
    //Other Configuration

    //Define and set typing attributes
    let style = NSMutableParagraphStyle()
    style.minimumLineHeight = lineHeight
    style.maximumLineHeight = lineHeight
    style.alignment = alignment
    style.lineHeightMultiple = 1.0
    typingAttributes = [NSParagraphStyleAttributeName: style, NSFontAttributeName: font]
  }

}

extension TextField: NSTextViewDelegate {
  func textView(_ textView: NSTextView, shouldChangeTextIn affectedCharRange: NSRange, replacementString: String?) -> Bool {
    if let oldText = textView.string, let replacement = replacementString {
      let newText = (oldText as NSString).replacingCharacters(in: affectedCharRange, with: replacement)
      let numberOfChars = newText.characters.count
      let wrongCharacterSet = CharacterSet(charactersIn: "0123456789").inverted
      let containsWrongCharacters = newText.rangeOfCharacter(from: wrongCharacterSet) != nil
      return numberOfChars <= 2 && !containsWrongCharacters
    }
    return false
  }
}

使用这个类，您只需将情节提要中的NSTextView 设置为该类，并更改属性和shouldChangeTextIn 以满足您的需要。在此实现中，“TextField”具有各种属性集，并且仅限于两个字符并且只有数字。

Answer 2

您将 NSNumberFormatter 子类化为以下内容：

final class ChargiePercentageNumberFormatter: NumberFormatter {

    override func attributedString(for obj: Any, withDefaultAttributes attrs: [NSAttributedString.Key : Any]? = nil) -> NSAttributedString? {
        guard let obj = obj as? NSNumber else {
            return nil;
        }
        guard let numberString = self.string(from: obj) else {
            return nil
        }
        let font = NSFont(name: "Poppins-Regular", size: 16)!
        let attrs: [NSAttributedString.Key: Any] = [.font: font, .kern: 1.2]

        let result = NSAttributedString(string: numberString, attributes: attrs)
        return result
    }

}