更多详情请看 NateCook 的回答>

func replace(myString: String, _ index: Int, _ newChar: Character) -> String {
    var chars = Array(myString.characters)     // gets an array of characters
    chars[index] = newChar
    let modifiedString = String(chars)
    return modifiedString
}

对于 Swift 5

func replace(myString: String, _ index: Int, _ newChar: Character) -> String {
    var chars = Array(myString)     // gets an array of characters
    chars[index] = newChar
    let modifiedString = String(chars)
    return modifiedString
}

replace("House", 2, "r")

这不再有效且已弃用.

您始终可以将 swift String 与 NSString 一起使用.因此您可以在 swift String 上调用 NSString 函数.通过旧的 stringByReplacingCharactersInRange: 你可以这样做

You can always use swift String with NSString.So you can call NSString function on swift String. By old stringByReplacingCharactersInRange: you can do like this

var st :String = "House"
let abc = st.bridgeToObjectiveC().stringByReplacingCharactersInRange(NSMakeRange(2,1), withString:"r") //Will give Horse