我正在开发一个使用 Facebook SDK 登录的 ios 应用程序。我已将 a 设置LogInViewController为 Storyboard 中的初始视图控制器，用户使用 FB 帐户登录。
我有另一个 ViewController，一旦用户登录，它就会正确加载。
在我正在检查的 AppDelegate 文件中currentAccessToken，如果它不为零，我将直接加载第二个 ViewController，因为用户已经登录。
但是，currentAccessToken如果我退出应用程序并重新启动它，它总是为零。只有当我按下主页按钮并在应用程序仍在后台运行时重新打开它时它才有效。
以下是代码中的详细信息：
AppDelegate.swift
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
self.customNavigationBar()
if (!isIcloudAvailable()) {
self.displayAlertWithTitle("iCloud", message: "iCloud is not available." +
" Please sign into your iCloud account and restart this app")
return true
}
if (FBSDKAccessToken.currentAccessToken() != nil) {
self.instantiateViewController("MapViewController", storyboardIdentifier: "Main")
}
return FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
}
func application(application: UIApplication, openURL url: NSURL, sourceApplication: String?, annotation: AnyObject) -> Bool {
return FBSDKApplicationDelegate.sharedInstance().application(
application,
openURL: url,
sourceApplication: sourceApplication,
annotation: annotation)
}
func applicationWillResignActive(application: UIApplication) {
FBSDKAppEvents.activateApp()
}
func applicationDidBecomeActive(application: UIApplication) {
FBSDKAppEvents.activateApp()
}
LogInViewController.swift
override func viewDidLoad() {
super.viewDidLoad()
// Listen to the Facebook notification and when received, execute func handleFBSessionStateChangeWithNotification
NSNotificationCenter.defaultCenter().addObserver(self, selector:"handleFBSessionStateChangeWithNotification:", name: "SessionStateChangeNotification", object: nil)
}
func handleFBSessionStateChangeWithNotification(notification: NSNotification) {
// Switch to MapViewController when logged in
if ((FBSDKAccessToken.currentAccessToken()) != nil) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let mapViewController = storyboard.instantiateViewControllerWithIdentifier("MapViewController") as! MapViewController
self.presentViewController(mapViewController, animated: false, completion: nil)
}
}
我不知道它是否相关，但我也收到了警告，MapViewController因为情节提要中没有针对它的 segue：
警告：尝试呈现其视图不在窗口层次结构中的 MapViewController！