Question

我正在尝试创建一个UIButton，以使选中的文本带有下划线。这是我当前的代码：

func underline() {
if let textRange = selectedRange {
    let attributedString = NSMutableAttributedString(attributedString: textView.attributedText)
    textView.textStorage.addAttributes([.underlineStyle : NSUnderlineStyle.single.rawValue], range: textRange)
    }
}

当前正在加下划线，但是我遇到的问题是我需要检查当前文本是否已加下划线，以及是否将其删除。我似乎无法通过NSMutableAttributedString来解决这个问题。

我正在使用斜体UIButton来做到这一点，

func italic() {
    if let textRange = selectedRange {
        let attributedString = NSAttributedString(attributedString: textView.attributedText)
        attributedString.enumerateAttribute(.font, in: textRange, options: []) { (font, range, pointee) in
            let newFont: UIFont
            if let font = font as? UIFont {
                let fontTraits = font.fontDescriptor.symbolicTraits
                if fontTraits.contains(.traitItalic) {
                    newFont = UIFont.systemFont(ofSize: font.pointSize, weight: .regular)
                } else {
                    newFont = UIFont.systemFont(ofSize: font.pointSize).italic()
                }
                textView.textStorage.addAttributes([.font : newFont], range: textRange)
            }
        }
    }
}

如何获得检查当前文本的第一个功能是否具有下划线属性的功能？

到目前为止的代码：

func isUnderlined(attrText: NSAttributedString) -> Bool {
    var contains: ObjCBool = false
    attrText.enumerateAttributes(in: NSRange(location: 0, length: attrText.length), options: []) { (dict, range, value) in
        if dict.keys.contains(.underlineStyle) {
            contains = true
        }
    }
    return contains.boolValue
}

func underline() {
    if let textRange = selectedRange {
        let attributedString = NSMutableAttributedString(attributedString: textView.attributedText)
        switch self.isUnderlined(attrText: attributedString) {
        case true:
            print("true")
            textView.textStorage.removeAttribute(.underlineStyle, range: textRange)
        case false:
            print("remove")
            textView.textStorage.addAttributes([.underlineStyle : NSUnderlineStyle.single.rawValue], range: textRange)
        }
    }
}

Answer 1

要检查文本是否已加下划线，只需对文本的属性（即

）运行 contains(_:)

func isUnderlined(attrText: NSAttributedString) -> Bool {
    var contains: ObjCBool = false
    attrText.enumerateAttributes(in: NSRange(location: 0, length: attrText.length), options: []) { (dict, range, value) in
        if dict.keys.contains(.underlineStyle) {
            contains = true
        }
    }
    return contains.boolValue
}

示例：

let attrText1 = NSAttributedString(string: "This is an underlined text.", attributes: [.underlineStyle : NSUnderlineStyle.styleSingle.rawValue])
let attrText2 = NSAttributedString(string: "This is an underlined text.", attributes: [.font : UIFont.systemFontSize])

print(self.isUnderlined(attrText: attrText1)) //true
print(self.isUnderlined(attrText: attrText2)) //false

您可以根据需要在UITextView中使用上述逻辑。

要删除该属性，

1。。首先，它必须是NSMutableAttributedString。

2。。然后，要删除属性，请对属性字符串使用removeAttribute(_:range:)方法。

let attrText1 = NSMutableAttributedString(string: "This is an underlined text.", attributes: [.underlineStyle : NSUnderlineStyle.styleSingle.rawValue])

print(self.isUnderlined(attrText: attrText1)) //true
if self.isUnderlined(attrText: attrText1) {
    attrText1.removeAttribute(.underlineStyle, range: NSRange(location: 0, length: attrText1.string.count))
}
print(self.isUnderlined(attrText: attrText1)) //false

点击按钮时textView的操作

@IBAction func onTapButton(_ sender: UIButton) {
    if let selectedTextRange = self.textView.selectedTextRange {
        let location = self.textView.offset(from: textView.beginningOfDocument, to: selectedTextRange.start)
        let length = self.textView.offset(from: selectedTextRange.start, to: selectedTextRange.end)
        let range = NSRange(location: location, length: length)

        self.textView.attributedText.enumerateAttributes(in: range, options: []) { (dict, range, value) in
            if dict.keys.contains(.underlineStyle) {
                self.textView.textStorage.removeAttribute(.underlineStyle, range: range)
            } else {
                self.textView.textStorage.addAttributes([.underlineStyle : NSUnderlineStyle.styleSingle.rawValue], range: range)
            }
        }
    }
}

枚举可变属性字符串（下划线按钮）

1 个答案: