如果您只需要一个唯一标识符UUID()。uuidString可以满足您的需求。

SwifterSwift有这个实现

/// SwifterSwift: Create a new random string of given length.
///
///     String(randomOfLength: 10) -> "gY8r3MHvlQ"
///
/// - Parameter length: number of characters in string.
init(randomOfLength length: Int) {
    guard length > 0 else {
        self.init()
        return
    }

    let base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    var randomString = ""
    for _ in 1...length {
        randomString.append(base.randomElement()!)
    }
    self = randomString
}

我做了一些改变，并使用这个实现

static func random(randomOfLength length: Int) -> String {
    guard length > 0 else { return "" }
    let base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    var randomString = ""
    for _ in 1...length {
        guard let randomCharacter = base.randomElement() else { continue }
        randomString.append(randomCharacter)
    }
    return randomString
}

为Swift 4更新。在类扩展上使用惰性存储变量。这只计算一次。

extension String {

    static var chars: [Character] = {
        return "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".map({$0})
    }()

    static func random(length: Int) -> String {
        var partial: [Character] = []

        for _ in 0..<length {
            let rand = Int(arc4random_uniform(UInt32(chars.count)))
            partial.append(chars[rand])
        }

        return String(partial)
    }
}

String.random(length: 10) //STQp9JQxoq

我对这个问题的更快速的回答是:

func randomAlphanumericString(length: Int) -> String {

    let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".characters
    let lettersLength = UInt32(letters.count)

    let randomCharacters = (0..<length).map { i -> String in
        let offset = Int(arc4random_uniform(lettersLength))
        let c = letters[letters.startIndex.advancedBy(offset)]
        return String(c)
    }

    return randomCharacters.joinWithSeparator("")
}

这里有一个Swiftier语法的现成解决方案。你可以简单地复制粘贴它:

func randomAlphaNumericString(length: Int) -> String {
    let allowedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    let allowedCharsCount = UInt32(allowedChars.characters.count)
    var randomString = ""

    for _ in 0 ..< length {
        let randomNum = Int(arc4random_uniform(allowedCharsCount))
        let randomIndex = allowedChars.index(allowedChars.startIndex, offsetBy: randomNum)
        let newCharacter = allowedChars[randomIndex]
        randomString += String(newCharacter)
    }

    return randomString
}

如果你喜欢一个框架，也有一些更方便的功能，然后随时签出我的项目handysswift。它还包括一个漂亮的随机字母数字字符串的解决方案:

String(randomWithLength: 8, allowedCharactersType: .alphaNumeric) // => "2TgM5sUG"

简单快捷——UUID().uuidString

//返回由UUID创建的字符串，例如"E621E1F8-C36C-495A-93FC-0C247A3E6E5F" uuidString:字符串{get} https://developer.apple.com/documentation/foundation/uuid

斯威夫特3.0

let randomString = UUID().uuidString //0548CD07-7E2B-412B-AD69-5B2364644433
print(randomString.replacingOccurrences(of: "-", with: ""))
//0548CD077E2B412BAD695B2364644433

EDIT

请不要与UIDevice.current.identifierForVendor混淆。uuidString它不会给出随机值。