如何將數據從appdelegate傳遞到ViewController？

Question

您好，我正在嘗試在IOS應用中實現推送通知功能。 目前，我有一些代碼，如果通過推送通知打開了應用程序，它將打開一個特定的viewcontroller。 我這樣做的方法是將ViewController推到頂部。

我現在需要做的是將數據從appdelegate傳遞到viewcontroller。 我知道將數據從viewcontroller傳遞到viewcontroller是使用prepareforsegue。 我嘗試這樣做，但是沒有用

我嘗試研究如何完成此任務，但是關於stackoverflow的許多答案都是過時的swift代碼，我無法轉換為swift3。有人可以向我解釋如何將數據從appdelegate發送到ViewController嗎？

這是顯示在didFinishLaunchingWithOptions中的VC的代碼

let storyboard = UIStoryboard(name: "Main", bundle: nil)

let destinationViewController = storyboard.instantiateViewController(withIdentifier: "detailPin2") as! detailPinViewController

let navigationController = self.window?.rootViewController as! UINavigationController

navigationController.pushViewController(destinationViewController, animated: false)

Answer 1

//Declare you variable  somewhere within the app delegate scope
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var myVariable: String = "Hello Swift"


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }
 // some other app delegate’s methods.... 

}

//In your view controller
class ViewController: UIViewController {

    @IBOutlet weak var myLabel: UILabel!
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let myOtherVariable = appDelegate.myVariable

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        myLabel.text = myOtherVariable
        var anotherVariable: String = appDelegate.myVariable // etc...

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

Answer 2

好的-您已經完成了大部分工作...

使用segues時，iOS會創建您的視圖控制器，並允許您在prepare中對其進行訪問，在其中您可能已執行了以下操作：

if let vc = segue.destination as? detailPinViewController {
     vc.myVariable = "this is the data to pass"  
}

在didFinishLaunchingWithOptions ，您正在執行創建部分和“表示”部分...，因此您只需添加“傳遞數據”部分：

let destinationViewController = storyboard.instantiateViewController(withIdentifier: "detailPin2") as! detailPinViewController

destinationViewController.myVariable = "this is the data to pass"

let navigationController = self.window?.rootViewController as! UINavigationController

navigationController.pushViewController(destinationViewController, animated: false)

那應該做到的。