OAuthGoogle.swift

// An example authorizing Google Api use with OAuthSwift https://github.com/OAuthSwift/OAuthSwift

import Foundation
import OAuthSwift // https://github.com/OAuthSwift/OAuthSwift
import KeychainAccess // https://github.com/kishikawakatsumi/KeychainAccess
import SwiftyJSON // https://github.com/SwiftyJSON/SwiftyJSON

class Google {
	
	private let auth: OAuth2Swift
	
	init(cKey: String) {
		auth = OAuth2Swift(consumerKey: cKey, // your consumer key from https://console.developers.google.com
													 consumerSecret: "", // leave blank
													 authorizeUrl: "https://accounts.google.com/o/oauth2/v2/auth",
													 accessTokenUrl: "https://www.googleapis.com/oauth2/v4/token",
													 responseType: "code")
		
		let bundleID = Bundle.main.bundleIdentifier!
		let keychain = Keychain(service: bundleID)
		
    // example to clear saved credentials
//		keychain["google_oauthToken"] = nil
//		keychain["google_oauthTokenSecret"] = nil
//		keychain["google_oauthRefreshToken"] = nil
		
    // setup oauth client if saved credentials exist
		if let token = keychain["google_oauthToken"],
			let tokenSecret = keychain["google_oauthTokenSecret"],
			let refreshToken = keychain["google_oauthRefreshToken"]
		{
			auth.client.credential.oauthToken = token
			auth.client.credential.oauthTokenSecret = tokenSecret
			auth.client.credential.oauthRefreshToken = refreshToken
			
		} else { // bring up auth dialog to get authorization tokens
//			auth.authorizeURLHandler = SafariURLHandler(viewController: viewController, oauthSwift: auth) // this fails
			auth.authorize(withCallbackURL: URL(string: "\(bundleId):/oauth2Callback")!, // setup your callback URL
										 scope: "https://www.googleapis.com/auth/calendar", // configure to the scope of api access you want to use
										 state: "test", // useless?
										 success: { (credential, response, parameters) in
                               
				// store tokens for future use in keychain using KeychainAccess
				keychain["google_oauthToken"] = credential.oauthToken
				keychain["google_oauthTokenSecret"] = credential.oauthTokenSecret
				keychain["google_oauthRefreshToken"] = credential.oauthRefreshToken
                               
        // example authorized request returning json of user's google calendars
        _ = auth.startAuthorizedRequest("https://www.googleapis.com/calendar/v3/users/me/calendarList",
          method: .GET, parameters: [:],
          success: { (response) in
            let json = JSON(data: response.data)
            print(json)
											
        }, failure: { (error) in
          print(error.localizedDescription)
        })
		}
	}
}