以字母

Question

我想用一个部分粗体的字符串设置标签的文本。我想要大胆的单词都以相同的字母开头，说“〜”。

例如，我可以使用字符串，“这个〜字是粗体，所以〜这个”

然后标签的文字将包含字符串“This word 是粗体，这个”也是如此。

有人知道是否可以制作这样的功能？我尝试了以下方法：

func makeStringBoldForLabel(str: String) {
    var finalStr = ""
    let words = str.components(separatedBy: " ")
    for var word in words {
        if word.characters.first == "~" {
            var att = [NSFontAttributeName : boldFont]
            let realWord = word.substring(from: word.startIndex)
            finalStr = finalStr + NSMutableAttributedString(string:realWord, attributes:att)
        } else {
            finalStr = finalStr + word
        }
    }
}

但得到错误：

Binary operator '+' cannot be applied to operands of type 'String' and 'NSMutableAttributedString'

Answer 1

易于解决问题。

使用：

func makeStringBoldForLabel(str: String) {
    let finalStr = NSMutableAttributedString(string: "")
    let words = str.components(separatedBy: " ")
    for var word in words {
        if word.characters.first == "~" {
            var att = [NSFontAttributeName : boldFont]
            let realWord = word.substring(from: word.startIndex)
            finalStr.append(NSMutableAttributedString(string:realWord, attributes:att))
        } else {
            finalStr.append(NSMutableAttributedString(string: word))
        }
    }
}

Answer 2

错误消息很明确，您无法将String和NSAttributedString与+运算符连接起来。

您正在寻找API enumerateSubstrings:options。它通过.byWords选项逐字枚举字符串。不幸的是，波浪号（~）不被识别为单词分隔符，因此我们必须检查单词是否具有前面的波形符号。然后更改特定范围的字体属性。

let string = "This ~word is bold, and so is ~this"

let attributedString = NSMutableAttributedString(string: string, attributes:[NSFontAttributeName : NSFont.systemFont(ofSize: 14.0)])
let boldAttribute = NSFont.boldSystemFont(ofSize: 14.0)

string.enumerateSubstrings(in: string.startIndex..<string.endIndex, options: .byWords) { (substring, substringRange, enclosingRange, stop) -> () in
    if substring == nil { return }
    if substringRange.lowerBound != string.startIndex {
        let tildeIndex = string.index(before: substringRange.lowerBound)
        if string[tildeIndex..<substringRange.lowerBound] == "~" {
            let location = string.distance(from: string.startIndex, to: tildeIndex)
            let length = string.distance(from: tildeIndex, to: substringRange.upperBound)
            attributedString.addAttribute(NSFontAttributeName, value: boldAttribute, range: NSMakeRange(location, length))
        }
    }
}