迅速扩展:

extension String {

    func stringByReplacing(replaceStrings set: [String], with: String) -> String {
        var stringObject = self
        for string in set {
            stringObject = self.stringByReplacingOccurrencesOfString(string, withString: with)
        }
        return stringObject
    }

}

继续使用let replacedString = yorString。stringbyreplacement (replaceStrings: [" "，"?"，"."]，加上:“+”)

函数的速度是我几乎不能感到骄傲的，但是你可以在一次传递一个String数组来进行多次替换。

如果你不想使用Objective-C NSString方法，你可以使用split和join:

var string = "This is my string"
string = join("+", split(string, isSeparator: { $0 == " " }))

split(string, isSeparator:{$0 == " "})返回一个字符串数组(["This"， "is"， "my"， "string"])。

join用一个+连接这些元素，产生所需的输出:"This+is+my+string"。

基于Ramis回答的Swift 3解决方案:

extension String {
    func withReplacedCharacters(_ characters: String, by separator: String) -> String {
        let characterSet = CharacterSet(charactersIn: characters)
        return components(separatedBy: characterSet).joined(separator: separator)
    }
}

尝试根据Swift 3的命名约定，提出一个合适的函数名。

Xcode 11•Swift 5.1

StringProtocol replacingOccurrences的突变方法可以实现如下:

extension RangeReplaceableCollection where Self: StringProtocol {
    mutating func replaceOccurrences<Target: StringProtocol, Replacement: StringProtocol>(of target: Target, with replacement: Replacement, options: String.CompareOptions = [], range searchRange: Range<String.Index>? = nil) {
        self = .init(replacingOccurrences(of: target, with: replacement, options: options, range: searchRange))
    }
}

var name = "This is my string"
name.replaceOccurrences(of: " ", with: "+")
print(name) // "This+is+my+string\n"

var str = "This is my string"
str = str.replacingOccurrences(of: " ", with: "+")
print(str)

你测试过这个吗?

var test = "This is my string"

let replaced = test.stringByReplacingOccurrencesOfString(" ", withString: "+", options: nil, range: nil)