ios – 在Swift中解码JSON Web令牌

尝试在 Swift中解码JWT有效负载并且遇到非常困难的时间

static func decodePayload(tokenstr: String) {

    //splitting JWT to extract payload
    let arr = split(tokenstr) {$0 == "."}

    //base64 encoded string i want to decode
    let base64String = arr[1] as String
    println(base64String) //eyJleHAiOjE0MjY4MjIxNjMsImlkIjoiNTUwYjA3NzM4ODk1NjAwZTk5MDAwMDAxIn0

    //attempting to convert base64 string to nsdata 
    let nsdata: NSData = NSData(base64EncodedString: base64String,options: NSDataBase64DecodingOptions(rawValue: 0))

    //decoding fails because nsdata unwraps as nil
    let base64Decoded: Nsstring = Nsstring(data: nsdata!,encoding: NSUTF8StringEncoding)!


}

解决方法

eyJleHAiOjE0MjY4MjIxNjMsImlkIjoiNTUwYjA3NzM4ODk1NjAwZTk5MDAwMDAxIn0

不是有效的Base64编码字符串,因为它的长度
不是4的倍数.一些Base64解码器容忍这个错误,但是
NSData方法没有.

所以这实际上是服务器端创建的错误
Base64编码的字符串.如有必要,您可以在应用中修复它
通过添加= =字符所需的填充(为Swift 2更新的代码)：

var base64String = arr[1] as String
if base64String.characters.count % 4 != 0 {
    let padlen = 4 - base64String.characters.count % 4
    base64String += String(count: padlen,repeatedValue: Character("="))
}

现在解码按预期工作：

if let data = NSData(base64EncodedString: base64String,options: []),let str = String(data: data,encoding: NSUTF8StringEncoding) {
    print(str) // {"exp":1426822163,"id":"550b07738895600e99000001"}
}

斯威夫特4：

var base64String = "eyJleHAiOjE0MjY4MjIxNjMsImlkIjoiNTUwYjA3NzM4ODk1NjAwZTk5MDAwMDAxIn0"

if base64String.count % 4 != 0 {
    let padlen = 4 - base64String.count % 4
    base64String.append(contentsOf: repeatElement("=",count: padlen))
}

if let data = Data(base64Encoded: base64String),encoding: .utf8) {
    print(str) // {"exp":1426822163,"id":"550b07738895600e99000001"}
}