swift 4中的错误

这是我的swift代码：

while ((mutatedString.range(of: "-")?.lowerBound) != nil) {
        if let range = mutatedString.range(of: "-") {
        let caseString = mutatedString.substring(with: range)
        let caseString = mutatedString.substring(with: <#T##String.CharacterView corresponding to your index##String.CharacterView#>.index(range.lowerBound, offsetBy: 1)..<.index(range.upperBound, offsetBy: 1))
                    mutatedString = mutatedString.replacingCharacters(in: range.lowerBound..<<#T##String.CharacterView corresponding to your index##String.CharacterView#>.index(range.upperBound, offsetBy: 1), with: caseString.uppercased())
                }
            }

占位符编辑器错误。。 谢谢

---

是自动完成中的编辑器占位符。您应该用变量替换它

文本中的查找编辑器占位符…什么错误？您的代码似乎有占位符。。。

<#T##String.CharacterView corresponding to your index##String.CharacterView#>