Ios 将base64URL解码为base64--Swift

我还没有找到在swift中将base64URL解码为base64格式的正确方法

根据

hJQWHABDBjoPHorYF5xghQ

（base64URL）应该是

hJQWHABDBjoPHorYF5xghQ==

（base64）。这里可能有更多的差异

没有关于stackoverflow的解决方案

“base64url”与标准Base64编码在两个方面不同：

• 索引62和63使用了不同的字符（

  -

  和
  ） 属于

  +

  和

  /

  ）
• 不必使用

  =

  字符强制填充字符串长度 四的倍数

（比较）

下面是一个可能的转换函数：

func base64urlToBase64(base64url: String) -> String {
    var base64 = base64url
        .replacingOccurrences(of: "-", with: "+")
        .replacingOccurrences(of: "_", with: "/")
    if base64.characters.count % 4 != 0 {
        base64.append(String(repeating: "=", count: 4 - base64.characters.count % 4))
    }
    return base64
}

例如：

let base64url = "hJQWHABDBjoPHorYF5xghQ"
let base64 = base64urlToBase64(base64url: base64url)
print(base64) // hJQWHABDBjoPHorYF5xghQ==

if let data = Data(base64Encoded: base64) {
    print(data as NSData) // <8494161c 0043063a 0f1e8ad8 179c6085>
}

---

Swift 4的更新：

func base64urlToBase64(base64url: String) -> String {
    var base64 = base64url
        .replacingOccurrences(of: "-", with: "+")
        .replacingOccurrences(of: "_", with: "/")
    if base64.count % 4 != 0 {
        base64.append(String(repeating: "=", count: 4 - base64.count % 4))
    }
    return base64
}

---

以下是Martin在Swift 4扩展中发布的内容的清理版本：

import Foundation

/// Extension for making base64 representations of `Data` safe for
/// transmitting via URL query parameters
extension Data {

    /// Instantiates data by decoding a base64url string into base64
    ///
    /// - Parameter string: A base64url encoded string
    init?(base64URLEncoded string: String) {
        self.init(base64Encoded: string.toggleBase64URLSafe(on: false))
    }

    /// Encodes the string into a base64url safe representation
    ///
    /// - Returns: A string that is base64 encoded but made safe for passing
    ///            in as a query parameter into a URL string
    func base64URLEncodedString() -> String {
        return self.base64EncodedString().toggleBase64URLSafe(on: true)
    }

}

extension String {

    /// Encodes or decodes into a base64url safe representation
    ///
    /// - Parameter on: Whether or not the string should be made safe for URL strings
    /// - Returns: if `on`, then a base64url string; if `off` then a base64 string
    func toggleBase64URLSafe(on: Bool) -> String {
        if on {
            // Make base64 string safe for passing into URL query params
            let base64url = self.replacingOccurrences(of: "/", with: "_")
                .replacingOccurrences(of: "+", with: "-")
                .replacingOccurrences(of: "=", with: "")
            return base64url
        } else {
            // Return to base64 encoding
            var base64 = self.replacingOccurrences(of: "_", with: "/")
                .replacingOccurrences(of: "-", with: "+")
            // Add any necessary padding with `=`
            if base64.count % 4 != 0 {
                base64.append(String(repeating: "=", count: 4 - base64.count % 4))
            }
            return base64
        }
    }

}

---

在右侧的“相关”部分下，有一个关于Base64URL通过JavaScript解码的链接。快速查看一下，您就会了解其中的区别。Mandrill自定义跟踪域，跟踪参数p也可以通过这种方式进行解码。注意像我这样的人：）谢谢！方便与来自Swift的GMail API交互。

toggleBase64URLSafe

一个非常奇怪的API，尤其是名称。为什么不把它分成两个独立的功能呢？

import Foundation

/// Extension for making base64 representations of `Data` safe for
/// transmitting via URL query parameters
extension Data {

    /// Instantiates data by decoding a base64url string into base64
    ///
    /// - Parameter string: A base64url encoded string
    init?(base64URLEncoded string: String) {
        self.init(base64Encoded: string.toggleBase64URLSafe(on: false))
    }

    /// Encodes the string into a base64url safe representation
    ///
    /// - Returns: A string that is base64 encoded but made safe for passing
    ///            in as a query parameter into a URL string
    func base64URLEncodedString() -> String {
        return self.base64EncodedString().toggleBase64URLSafe(on: true)
    }

}

extension String {

    /// Encodes or decodes into a base64url safe representation
    ///
    /// - Parameter on: Whether or not the string should be made safe for URL strings
    /// - Returns: if `on`, then a base64url string; if `off` then a base64 string
    func toggleBase64URLSafe(on: Bool) -> String {
        if on {
            // Make base64 string safe for passing into URL query params
            let base64url = self.replacingOccurrences(of: "/", with: "_")
                .replacingOccurrences(of: "+", with: "-")
                .replacingOccurrences(of: "=", with: "")
            return base64url
        } else {
            // Return to base64 encoding
            var base64 = self.replacingOccurrences(of: "_", with: "/")
                .replacingOccurrences(of: "-", with: "+")
            // Add any necessary padding with `=`
            if base64.count % 4 != 0 {
                base64.append(String(repeating: "=", count: 4 - base64.count % 4))
            }
            return base64
        }
    }

}