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)

你可以用这个:

let s = "This is my string"
let modified = s.replace(" ", withString:"+")    

如果你在你的代码中添加这个扩展方法:

extension String
{
    func replace(target: String, withString: String) -> String
    {
       return self.stringByReplacingOccurrencesOfString(target, withString: withString, options: NSStringCompareOptions.LiteralSearch, range: nil)
    }
}

斯威夫特3:

extension String
{
    func replace(target: String, withString: String) -> String
    {
        return self.replacingOccurrences(of: target, with: withString, options: NSString.CompareOptions.literal, range: nil)
    }
}

Swift 4和5已经更新了这个答案。如果你还在使用Swift 1、2或3，请查看修订历史。

你有两个选择。你可以像@jaumard建议的那样，使用replacingOccurrences()

let aString = "This is my string"
let newString = aString.replacingOccurrences(of: " ", with: "+", options: .literal, range: nil)

正如下面@cprcrack所指出的，选项和范围参数是可选的，所以如果您不想指定字符串比较选项或执行替换的范围，您只需要以下内容。

let aString = "This is my string"
let newString = aString.replacingOccurrences(of: " ", with: "+")

或者，如果数据是这样的特定格式，其中只是替换分隔符，则可以使用components()将字符串拆分为一个数组，然后可以使用join()函数将它们与指定的分隔符组合在一起。

let toArray = aString.components(separatedBy: " ")
let backToString = toArray.joined(separator: "+")

或者如果你正在寻找一个更Swifty的解决方案，不利用NSString的API，你可以使用这个。

let aString = "Some search text"

let replaced = String(aString.map {
    $0 == " " ? "+" : $0
})

斯威夫特4:

let abc = "Hello world"

let result = abc.replacingOccurrences(of: " ", with: "_", 
    options: NSString.CompareOptions.literal, range:nil)

print(result :\(result))

输出:

result : Hello_world

斯威夫特5.5

我正在使用这个扩展:

extension String {

    func replaceCharacters(characters: String, toSeparator: String) -> String {
        let characterSet = CharacterSet(charactersIn: characters)
        let components = components(separatedBy: characterSet)
        let result = components.joined(separator: toSeparator)
        return result
    }

    func wipeCharacters(characters: String) -> String {
        return self.replaceCharacters(characters: characters, toSeparator: "")
    }
}

用法:

"<34353 43434>".replaceCharacters(characters: "< >", toSeparator:"+") // +34353+43434+
"<34353 43434>".wipeCharacters(characters: "< >") // 3435343434