我如何在Swift中生成一个随机的字母数字字符串?
当前回答
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
其他回答
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
}
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"
在Swift 4.2中,你最好的方法是创建一个包含你想要的字符的字符串,然后使用randomElement来选择每个字符:
let length = 32
let characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let randomCharacters = (0..<length).map{_ in characters.randomElement()!}
let randomString = String(randomCharacters)
我将在这里详细介绍这些变化。
斯威夫特5.6
此函数生成一个以36为基数的10位数字,然后将其作为字母数字字符串返回。
func randomCode(length: Int) -> String {
let radix = 36 // = 10 digits + 26 letters
let number = Int.random(in: 0..<(pow(radix, length)))
return String(number, radix: radix, uppercase: true)
}
或者如果你不希望代码以“0”开头:
func randomCode(length: Int) -> String {
let radix = 36 // = 10 digits + 26 letters
let range = (pow(radix, length)/2)..<(pow(radix, length))
let number = Int.random(in: range)
return String(number, radix: radix, uppercase: true)
}
针对Swift 3.0
func randomString(_ length: Int) -> String {
let letters : NSString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let len = UInt32(letters.length)
var randomString = ""
for _ in 0 ..< length {
let rand = arc4random_uniform(len)
var nextChar = letters.character(at: Int(rand))
randomString += NSString(characters: &nextChar, length: 1) as String
}
return randomString
}