• Finish setting up the OAuth2 protocol to access a user's GitHub account

• Add the following five files to this project from your completed version of the part one lab:
• AppDelegate.swift
• GitHubAPIClient.swift
• Info.plist
• LoginViewController.swift
• Secrets.swift

• Add the following methods to the GitHubAPIClient extension marked "OAuth"

// Start access token request process
class func startAccessTokenRequest(url url: NSURL, completionHandler: (Bool) -> ()) {

}

// Save access token from request response to keychain
private class func saveAccess(token token: String, completionHandler: (Bool) -> ()) {

}

// Get access token from keychain      
private class func getAccessToken() -> String? {

        return nil

}

// Delete access token from keychain
class func deleteAccessToken(completionHandler: (Bool) -> ()) {

}

At the end of the last lab you received a temporary code back from GitHub. You are going to use that code to make a request to GitHub for the access token.

• Inside the safariLogin(_:) method of the LoginViewController, call the startAccessTokenRequest(url:completionHandler:) method from the GitHubAPIClient.
• Pass the URL received back from GitHub to the url parameter of the startAccessTokenRequest(url:completionHandler:) method.
• Hint: Remember the notification argument passed in from safariLogin(_:) has the url stored in the object property.
• Head over to the GitHubAPIClient class to define the startAccessTokenRequest(url:completionHandler:) method.
• Use this order of tasks to define the method:
  • Use the NSURL extension from the Extensions file to extract the code.
  • Build your parameter dictionary for the request.
    • "client_id": your client id
    • "client_secret": your client secret
    • "code": temporary code from GitHub
  • Build your headers dictionary to receive JSON data back.
    • "Accept": "application/json"
  • Use request(_:_:parameters:encoding:headers:) from Alamofire to make a POST request using the .token string from the URLRouter, the parameter dictionary, and the header dictionary.
  • If the request is successful, print response and call completionHandler(true), else completionHandler(false).
• Run the application to see if you are getting a successful response.

• Use SwiftyJSON to get the access token from the response you were working with in the previous step.
• Call saveAccess(token:completionHandler:) to pass the access token you retrieved from the JSON data.
• Define the saveAccess(token:completionHandler:) method using the Locksmith pod. Use the method, try Locksmith.saveData(["some key": "some value"], forUserAccount: "myUserAccount").
  • Key is "access token". Value is "token from response". User account is "github".
  • The completionHandler should callback with true or false depending on whether the access token is saved successfully.
• Back inside the response section of the startAccessTokenRequest(url:completionHandler:) method, update the order of tasks to be:
  • Receive response.
  • Serialize JSON data using SwiftyJSON.
  • Call saveAccess(token:completionHandler:) method.
  • If save succeeded, call the completion handler of startAccessTokenRequest(url:completionHandler:) with the appropriate response.
  • Run the application using print statements accordingly to see that everything is working correctly.

• Use the Locksmith method, Locksmith.loadDataForUserAccount() to retrieve the access token and return it.
• Update the starred(repoName:) static function defined in the URLRouter enum.
  • starredURL needs to be combined with the access token for user account requests.
• Update the hasToken() method to check if there is a token saved.
  • Use getAccessToken() to determine whether the method should return true or false.
• Reset the simulator and run the application. At this point you should be able to log in again. Stop the application. Run it again and you should be directed to the table view controller containing a list of repositories.

Resetting the simulator and rerunning the application will indicate if everything is working correctly but it's not ideal. There are a few more pieces to this puzzle that can make it complete. Here's what's left:

• Login

  • The LoginViewController starts the login process BUT the AppController doesn't know about the outcome of the process. That means it doesn't know whether it should display the table view controller or not. startAccessTokenRequest(url:completionHandler:) is called inside the LoginViewController with a callback about whether the process succeeded. If it succeeds, post a notification using the appropriate Notification name. The AppController already has the observer set up.

• Logout

  • The ReposTableViewController has an IBAction for the log out button. This method needs to call deleteAccessToken(_:) from GitHubAPIClient and use the completion handler to determine whether to post a notification to the AppController to close the table view controller. deleteAccessToken still needs to be defined. It should delete the token and call back with the outcome.