通过“推送通知”从“终止”状态打开应用程序时，iOS Web View App崩溃

Question

My app is crash when open from kill state through Push Notification . It works good if app is launched already but when app is killed then if got any push notification and I tap on it, it crash the app. I did not find any error, can any one help me to solve this?

If I comment then UNUserNotificationCenter code from didFinishLaunchingWithOptions in AppDelegate.swift then app not crashing but then view is not loaded against notification. I send the url in push notification and check it not blank then load it as view.

AppDelegate.swift

import UIKit
import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {

    var window: UIWindow?
    var apiUrl = "http://www.example.com/api/";

    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        let token = deviceToken.map { String(format: "%02.2hhx", $0) }.joined()
        // Device Registration with API
        deviceRegistration(token)
        //print("Token: \(token)")
    }

    func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {

    }

    // Device Registration with API 
    func deviceRegistration(_ token: String) {
        let parameters = ["UUID": UIDevice.current.identifierForVendor!.uuidString, "Token": token, "DevOption": "Dev", "MID": "0"]
        let url = URL(string: apiUrl + "ios-register")!

        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")

        let httpBody = try? JSONSerialization.data(withJSONObject: parameters, options: [])
        request.httpBody = httpBody

        let session = URLSession.shared.dataTask(with: request) { (data, response, error) in
            if let data = data {
                do {
                    let json = try JSONSerialization.jsonObject(with: data, options: [])
                    print(json)
                } catch {
                }
            }
        }
        session.resume()
    }

    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.alert, .sound])
    }

    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {

        // Check User Tap the notification
        if let notification = response.notification.request.content.userInfo as? [String: AnyObject] {
            let message = parseRemoteNotification(notification: notification)

            guard let url = message?["url"] as? String else {
                return;
            }
            // If url exists then load the url
            if !(url.isEmpty) {
                loadView(url)
            }
        }
        completionHandler()
    }

    private func parseRemoteNotification(notification:[String:AnyObject]) -> NSDictionary? {
        if let aps = notification["aps"] as? [String:AnyObject] {
            let alert = aps["alert"] as? NSDictionary
            return alert
        }
        return nil
    }

    func loadView(_ url: String) {
        let data: [String: String] = ["url": url]
        NotificationCenter.default.post(name: NSNotification.Name("loadWebView"), object: nil, userInfo: data)
    }

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        if let sb = UIApplication.shared.value(forKeyPath: "statusBarWindow.statusBar") as? UIView {
            sb.backgroundColor = UIColor.init(red: 252/255, green: 153/255, blue: 0/255, alpha: 1)
        }

        // Local Notification
        //if(application.applicationState == .active) {
            UNUserNotificationCenter.current().delegate = self
            UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound]) { (granted, error) in
                //print("Granted: \(granted)")
            }
        //}

        // Push Notifications
        UIApplication.shared.registerForRemoteNotifications()

        return true
    }

    func applicationWillResignActive(_ application: UIApplication) {
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    }

    func applicationWillEnterForeground(_ application: UIApplication) {
        // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    }

    func applicationWillTerminate(_ application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }


}

ViewControllwer.swift

import UIKit
import WebKit
import UserNotifications

class ViewController: UIViewController, WKNavigationDelegate {

    @IBOutlet var mWebKit: WKWebView!
    @IBOutlet var indicator: UIActivityIndicatorView!

    public var defaultUrl = "https://www.example.com";
    public var viewUrl = URL(string: "https://www.example.com")!

    override func viewDidLoad() {
        super.viewDidLoad()

        mWebKit.navigationDelegate = self
        self.mWebKit.addObserver(self, forKeyPath: "URL", options: .new, context: nil)
        self.mWebKit.addObserver(self, forKeyPath: "estimatedProgress", options: .new, context: nil)

        loadWebView(viewUrl)

        // On Notification Receive
        NotificationCenter.default.addObserver(forName: NSNotification.Name("loadWebView"), object: nil, queue: nil) { (Notification) in
            //print("notification is \(Notification)")
            let url = URL(string: Notification.userInfo?["url"] as? String ?? self.defaultUrl)
            self.loadWebView(url ?? self.viewUrl)
        }

        // Do any additional setup after loading the view, typically from a nib.
    }

    func loadWebView(_ url: URL) {
        var request = URLRequest(url: url)
        request.setValue("com.example.in", forHTTPHeaderField: "X-REQUESTED-WITH")
        self.mWebKit.load(request)
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

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

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == #keyPath(WKWebView.url) {
            indicator.startAnimating()            
            loadWebView(self.mWebKit.url!)
        }

        if keyPath == #keyPath(WKWebView.estimatedProgress) {
            if(self.mWebKit.estimatedProgress == 1) {
                indicator.stopAnimating()
            }
        }
    }

}

Answer 1

Here, I am not posting actual solution for your answer, but posting the way in which you can atleast debug your code. So, If you are able to keep breakpoints and can able to see the logs(by using print method), then, you can easily find the actual cause behind the scene.

Here is way for debugging such case.

1. Go to edit scheme

2. Now, The screen which get opened, here select Run from the left menu. Now, Select Info tab from top menu. Here you will see 2 Radio buttons for Launch case. Automatically will be selected by default. Change it to Wait for executable to be launched . Then close this screen.

3. Now, run your app in your device. It will install your app on device, but it will not launch your app, as it commonly do everytime.

4. Now, post your push notification, once you will receive the notification, click on it. As you click on it, your app will get launched, and your debugging session will start, if your app is crashing, then breakpoint will automatically stops there. Otherwise, if there is any issue with your logic, you can debug the session by putting the breakpoints as well as by adding "print" logs, wherever required.

I think by doing above thing, you will be able to debug and once you can debug, you can easily identify the issue and have the solution. Once you get the solution, change the above setting back to Automatically to launch your app normally.