iOS Swift Toggle属性字符串的下划线

Question

I hav written two fuction to Add underline to a String and remove underline :

I want to toggle underline with a button. So how do I check if NSMutableAttributedString has underline attribute :

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

You can check by calling the function .enumerateAttribute(attrName:, inRange:, options:, usingBlock:) on the NSMutableAttributedString you get in as the parameter:

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
}

Also, you can shorten your first function to a single line:

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

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As an aside, your code does not conform to the Swift style guidelines proposed by the Swift community.