斯威夫特5.5

但这在早期版本中可能有效。

我经常替换，因为我想用_或类似的东西替换“任何空白或-”。这个对字符串的扩展让我做到了。

extension String {
    func removingCharacters(_ characters:CharacterSet) -> Self {
        Self(self.unicodeScalars.filter {
            !characters.contains($0)
        })
    }
    func removingCharacters(in string:String) -> Self {
        Self(self.unicodeScalars.filter {
            !CharacterSet(charactersIn:string).contains($0)
        })
    }
    
    func replacingCharacters(_ characters:CharacterSet, with newChar:Character) -> Self {
        String(self.compactMap( {
            CharacterSet(charactersIn: "\($0.1)").isSubset(of: characters)
             ? newChar : $0.1
        }))
    }
    
    func replacingCharacters(in string:String, with newChar:Character) -> Self {
        String(self.compactMap( {
            CharacterSet(charactersIn: "\($0)").isSubset(of: CharacterSet(charactersIn:string))
             ? newChar : $0
        }))
    }
}

用法:

print("hello \n my name\t is Joe".removingCharacters(.whitespacesAndNewlines))
print("hello \n my name\t is Joe".removingCharacters(in: " \t\n"))

print("ban annan anann ana".replacingCharacters(.whitespacesAndNewlines, with: "_"))
print("ban-annan anann ana".replacingCharacters(in: " -", with: "_"))

显然，对于单个字符，. replacingoccurrences (of: " "， with: "+")更好。

我没有做过性能比较

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

风格做在Ramis的扩展。如果有人愿意，我会很感兴趣的。

参见替换表情符号:https://stackoverflow.com/a/63416058/5946596

下面是Swift 3的示例:

var stringToReplace = "This my string"
if let range = stringToReplace.range(of: "my") {
   stringToReplace?.replaceSubrange(range, with: "your")
} 

你测试过这个吗?

var test = "This is my string"

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

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"

这是一个在字符串上的替换方法的扩展，它没有不必要的复制，并在适当的地方做所有事情:

extension String {
    mutating func replaceOccurrences<Target: StringProtocol, Replacement: StringProtocol>(of target: Target, with replacement: Replacement, options: String.CompareOptions = [], locale: Locale? = nil) {
        var range: Range<Index>?
        repeat {
            range = self.range(of: target, options: options, range: range.map { self.index($0.lowerBound, offsetBy: replacement.count)..<self.endIndex }, locale: locale)
            if let range = range {
                self.replaceSubrange(range, with: replacement)
            }
        } while range != nil
    }
}

(方法签名也模仿内置String.replacingOccurrences()方法的签名)

可用于以下方式:

var string = "this is a string"
string.replaceOccurrences(of: " ", with: "_")
print(string) // "this_is_a_string"