Ios Swift 切换属性字符串的下划线

Question

我写了两个函数来为字符串添加下划线和删除下划线:

我想用一个按钮切换下划线。那么如何检查 NSMutableAttributedString 是否具有下划线属性:

func addUlnTxtFnc(TxtPsgVal :String) -> NSMutableAttributedString
{
    let TxtRngVal = NSMakeRange(0, TxtPsgVal.characters.count)
    let TxtUnlVal = NSMutableAttributedString(string: TxtPsgVal)
    TxtUnlVal.addAttribute(NSUnderlineStyleAttributeName, value:NSUnderlineStyle.StyleSingle.rawValue, range: TxtRngVal)

    return TxtUnlVal
}

func rmvUlnTxtFnc(TxtPsgVal :NSMutableAttributedString) -> NSMutableAttributedString
{
    let TxtRngVal = NSMakeRange(0, TxtPsgVal.string.Len())
    TxtPsgVal.removeAttribute(NSUnderlineStyleAttributeName, range: TxtRngVal)

    return TxtPsgVal
}

Answer 1

您可以通过在 NSMutableAttributedString 上调用函数 .enumerateAttribute(attrName:, inRange:, options:, usingBlock:) 作为参数进行检查:

func rmvUlnTxtFnc(TxtPsgVal: NSMutableAttributedString) -> NSMutableAttributedString {
    let TxtRngVal = NSMakeRange(0, TxtPsgVal.length)
    TxtPsgVal.enumerateAttribute(NSUnderlineStyleAttributeName, inRange: TxtRngVal, options: .LongestEffectiveRangeNotRequired) { attribute, range, pointer in
        if attribute != nil {
            TxtPsgVal.removeAttribute(NSUnderlineStyleAttributeName, range: range)
        }
    }
    return TxtPsgVal
}

此外，您可以将第一个函数缩短为一行:

func addUlnTxtFnc(TxtPsgVal: String) -> NSMutableAttributedString {
    return NSMutableAttributedString(string: TxtPsgVal, attributes: [NSUnderlineStyleAttributeName: NSUnderlineStyle.StyleSingle.rawValue])
}

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顺便说一句，您的代码不符合 Swift style guidelines由 Swift 社区提出。