How do I decode the JWT (JSON Web token) token in SWIFT?

 let jwt = try decode(jwt: token)

func decode(jwtToken jwt: String) -> [String: Any] {
 let segments = jwt.components(separatedBy: ".")
 return decodeJWTPart(segments[1]) ?? [: ]
}

func base64UrlDecode(_ value: String) -> Data? {
 var base64 = value
 .replacingOccurrences(of: "-", with: "+")
 .replacingOccurrences(of: "_", with: "/")< br />
 let length = Double(base64.lengthOfBytes(using: String.Encoding.utf8))
 let requiredLength = 4 * ceil(length / 4.0)
 let paddingLength = requiredLength-length 
 if paddingLength> 0 {
 let padding = "".padding(toLength: Int(paddingLength), withPad: "=", startingAt: 0)
 base64 = base64 + padding
 }
 return Data(base64Encoded: base64, options: .ignoreUnknownCharacters)
}

func decodeJWTPart(_ value: String) -> [String: Any]? {
 guard let bodyData = base64UrlDecode(value),
 let json = try? JSONSerialization.jsonObject(with: bodyData, options: []), let payload = json as? [String: Any] else {
 return nil
 }

 return payload
}

decode (jwtToken: TOKEN)

I have this kind of JWT token

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTYWiRGiViWiR4WiRg9ViVi .TJVA95OrM7E2cBab30RM HrHDcEfxjoYZgeFONFh7HgQ

How do I decode this so that I can get the payload like this

{ “sub”: “1234567890” , “Name”: “John Doe”, “admin”: true }

If you have no problem using the library, I would suggest This https://github.com/auth0/JWTDecode.swift

Then import the library to import JWTDecode and execute it.

let jwt = try decode(jwt: token)

Since you don’t want to include this library, I have provided the required parts to make it work.

func decode( jwtToken jwt: String) -> [String: Any] {
 let segments = jwt.components(separatedBy: ".")
 return decodeJWTPart(segments[1]) ?? [:]
}

func base64UrlDecode(_ value: String) -> Data? {
 var base64 = value
 .replacingOccurrences(of: "-", with: "+") 
 .replacingOccurrences(of: "_", with: "/")

 let length = Double(base64.lengthOfBytes(using: String.Encoding.utf8))
 let requiredLength = 4 * ceil(length / 4.0)
 let paddingLength = requiredLength-length
 if paddingLength> 0 {
 let padding = "".padding(toLength: Int(p addingLength), withPad: "=", startingAt: 0)
 base64 = base64 + padding
 }
 return Data(base64Encoded: base64, options: .ignoreUnknownCharacters)
}

func decodeJWTPart(_ value: String) -> [String: Any]? {
 guard let bodyData = base64UrlDecode(value),
 let json = try? JSONSerialization.jsonObject(with : bodyData, options: []), let payload = json as? [String: Any] else {
 return nil
 }

 return payload
} 
Call it like this:
 
 
decode(jwtToken: TOKEN)