我如何在Swift中生成一个随机的字母数字字符串?
当前回答
如果你的随机字符串应该是安全随机的,使用这个:
import Foundation
import Security
// ...
private static func createAlphaNumericRandomString(length: Int) -> String? {
// create random numbers from 0 to 63
// use random numbers as index for accessing characters from the symbols string
// this limit is chosen because it is close to the number of possible symbols A-Z, a-z, 0-9
// so the error rate for invalid indices is low
let randomNumberModulo: UInt8 = 64
// indices greater than the length of the symbols string are invalid
// invalid indices are skipped
let symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
var alphaNumericRandomString = ""
let maximumIndex = symbols.count - 1
while alphaNumericRandomString.count != length {
let bytesCount = 1
var randomByte: UInt8 = 0
guard errSecSuccess == SecRandomCopyBytes(kSecRandomDefault, bytesCount, &randomByte) else {
return nil
}
let randomIndex = randomByte % randomNumberModulo
// check if index exceeds symbols string length, then skip
guard randomIndex <= maximumIndex else { continue }
let symbolIndex = symbols.index(symbols.startIndex, offsetBy: Int(randomIndex))
alphaNumericRandomString.append(symbols[symbolIndex])
}
return alphaNumericRandomString
}
其他回答
你也可以这样使用它:
extension String {
static func random(length: Int = 20) -> String {
let base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
var randomString: String = ""
for _ in 0..<length {
let randomValue = arc4random_uniform(UInt32(base.characters.count))
randomString += "\(base[base.startIndex.advancedBy(Int(randomValue))])"
}
return randomString
}
}
简单的用法:
let randomString = String.random()
Swift 3语法:
extension String {
static func random(length: Int = 20) -> String {
let base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
var randomString: String = ""
for _ in 0..<length {
let randomValue = arc4random_uniform(UInt32(base.characters.count))
randomString += "\(base[base.index(base.startIndex, offsetBy: Int(randomValue))])"
}
return randomString
}
}
Swift 4语法:
extension String {
static func random(length: Int = 20) -> String {
let base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
var randomString: String = ""
for _ in 0..<length {
let randomValue = arc4random_uniform(UInt32(base.count))
randomString += "\(base[base.index(base.startIndex, offsetBy: Int(randomValue))])"
}
return randomString
}
}
如果你的随机字符串应该是安全随机的,使用这个:
import Foundation
import Security
// ...
private static func createAlphaNumericRandomString(length: Int) -> String? {
// create random numbers from 0 to 63
// use random numbers as index for accessing characters from the symbols string
// this limit is chosen because it is close to the number of possible symbols A-Z, a-z, 0-9
// so the error rate for invalid indices is low
let randomNumberModulo: UInt8 = 64
// indices greater than the length of the symbols string are invalid
// invalid indices are skipped
let symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
var alphaNumericRandomString = ""
let maximumIndex = symbols.count - 1
while alphaNumericRandomString.count != length {
let bytesCount = 1
var randomByte: UInt8 = 0
guard errSecSuccess == SecRandomCopyBytes(kSecRandomDefault, bytesCount, &randomByte) else {
return nil
}
let randomIndex = randomByte % randomNumberModulo
// check if index exceeds symbols string length, then skip
guard randomIndex <= maximumIndex else { continue }
let symbolIndex = symbols.index(symbols.startIndex, offsetBy: Int(randomIndex))
alphaNumericRandomString.append(symbols[symbolIndex])
}
return alphaNumericRandomString
}
斯威夫特5.0
// Generating Random String
func randomString(length: Int) -> String {
let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
return String((0..<length).map{ _ in letters.randomElement()! })
}
// Calling to string
label.text = randomString(length: 3)
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"
Swift 2.2版本
// based on https://gist.github.com/samuel-mellert/20b3c99dec168255a046
// which is based on https://gist.github.com/szhernovoy/276e69eb90a0de84dd90
// Updated to work on Swift 2.2
func randomString(length: Int) -> String {
let charactersString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let charactersArray : [Character] = Array(charactersString.characters)
var string = ""
for _ in 0..<length {
string.append(charactersArray[Int(arc4random()) % charactersArray.count])
}
return string
}
基本上调用这个方法,它将生成一个随机字符串,长度为传递给函数的整数。要更改可能的字符,只需编辑charactersString字符串。也支持unicode字符。
https://gist.github.com/gingofthesouth/54bea667b28a815b2fe33a4da986e327
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