Swift / iOS JWT Generator

Swift / iOS JWT generator quickstart

Create a token with your public API key in the sub claim, a near-term Unix timestamp in exp, and an HS256 signature made with your private API key.

Sapling JWTs use HS256 with a sub claim containing your public API key and an exp claim containing a Unix timestamp. The examples use a one-hour lifetime; shorten it further when your application can refresh tokens easily.

Swift / iOS HS256 · sub + exp

This example uses JWTKit 5 with Swift 6 or newer.

import Foundation
import JWTKit

struct SaplingClaims: JWTPayload {
  let sub: SubjectClaim
  let exp: ExpirationClaim

  func verify(using algorithm: some JWTAlgorithm) async throws {
    try exp.verifyNotExpired()
  }
}

@main
struct Main {
  static func main() async throws {
    guard let publicKey = ProcessInfo.processInfo.environment["SAPLING_PUBLIC_KEY"],
          let privateKey = ProcessInfo.processInfo.environment["SAPLING_PRIVATE_KEY"] else {
      throw NSError(
        domain: "Quickstart",
        code: 1,
        userInfo: [
          NSLocalizedDescriptionKey:
            "Set SAPLING_PUBLIC_KEY and SAPLING_PRIVATE_KEY first."
        ]
      )
    }

    let keys = JWTKeyCollection()
    await keys.add(hmac: privateKey, digestAlgorithm: .sha256)
    let claims = SaplingClaims(
      sub: SubjectClaim(value: publicKey),
      exp: ExpirationClaim(value: Date().addingTimeInterval(3600))
    )

    print(try await keys.sign(claims))
  }
}

Generated token text/plain

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.<base64url-claims>.<signature>

Return the compact token to the browser and pass it to Sapling.init as the key. Issue a fresh token after it expires; never send the private key.

Reference Frontend key management and JWT documentation All languages Choose another quickstart

About Swift / iOS

Swift is a compiled programming language developed by Apple as a replacement for Objective-C. It is used with Cocoa and Cocoa Touch frameworks for application development for iOS and macOS platforms.