Detect app crashed during load / last time it was run?

Question

I would like for my app to reset to standard settings if it crashed during startup. Preferably also if it crashed last time it was run.

EDIT: Critte

Answer 1

Make 2 functions in your AppDelegate.m file:

void HandleException(NSException *exception) {
    NSLog(@"App crashing with exception: %@", exception);
    //Save somewhere that your app has crashed.
}

void HandleSignal(int signal) {
    NSLog(@"We received a signal: %d", signal);
    //Save somewhere that your app has crashed.
}

Then in your -(BOOL)application:didFinishLaunchingWithOptions before anything else put:

NSSetUncaughtExceptionHandler(&HandleException);

struct sigaction signalAction;
memset(&signalAction, 0, sizeof(signalAction));
signalAction.sa_handler = &HandleSignal;

sigaction(SIGABRT, &signalAction, NULL);
sigaction(SIGILL, &signalAction, NULL);
sigaction(SIGBUS, &signalAction, NULL);

Answer 2

Using Crashlytics you then can set CrashlyticsDelegate to detect a crash on Swift or ObjC code.

import Fabric
import Crashlytics
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool
{
    Crashlytics.sharedInstance().delegate = self
    Fabric.with([Crashlytics.self])
    return true
}

//MARK: - CrashlyticsDelegate

func crashlyticsDidDetectReport(forLastExecution report: CLSReport, completionHandler: @escaping (Bool) -> Void)
{
    completionHandler(true)
}

From Crashlytics docs

Your delegate must invoke the completionHandler, but does not need to do so synchronously, or even on the main thread. Invoking completionHandler with NO will cause the detected report to be deleted and not submitted to Crashlytics. This is useful for implementing permission prompts, or other more-complex forms of logic around submitting crashes.

Make certain that the delegate is setup before starting Crashlytics with startWithAPIKey:… or via [Fabric with:…]. Failure to do will result in missing any delegate callbacks that occur synchronously during start.