Implementing Lifecycle metrics in iOS

For implementation details, please reference Register Lifecycle with Mobile Core and Add Appropriate Start/Pause calls.

Tracking app crashes in iOS

This information helps you understand how crashes are tracked and the best practices to handle false crashes.

Important: You should upgrade to Adobe Experience Platform SDKs, which contains critical changes that prevent false crashes from being reported.

How does crash reporting work?

When creating a new lifecycle session, the SDK looks for a variable it maintains in NSUserDefaults that indicates the previous session was paused. If the flag is not set, then the ensuing launch will also be treated as a crash.

The variable is controlled by calls to lifecyclePause (which sets the flag) and lifecycleStart (which clears the flag).

Why does Adobe measure crashes this way?

This approach of measuring crashes provides a high-level answer to the question, Did the user exit my app intentionally?

Crash reporting libraries provided by companies such as Apteligent (formerly Crittercism) use a global NSException handler to provide more detailed crash reporting. Your app is not allowed to have more than one of these kinds of handlers. Adobe decided to not implement a global NSException handler to prevent build errors, knowing that our customers might be using other crash reporting providers.

What can cause a false crash to be reported?

The following scenarios are known to falsely cause a crash to be reported by the SDK:

• If you are debugging using Xcode, re-launching the app while it is running in the foreground will cause a crash.

Tip: You can avoid a crash in this scenario by backgrounding the app prior to re-launching the app from Xcode.

• If your app is launched in the background because of an enabled background capability (e.g. - background fetch, location update), then lifecycleStart is called and the app never comes to the foreground, the next launch (whether in the background or foreground) will result in a crash.

• If you programmatically delete Adobe’s pause flag from NSUserDefaults, while the app is in the background, the next launch or resume causes a crash.

How can I prevent false crashes from being reported?

The following practices can help prevent false crashes from being reported:

• Perform your development against non-production report suites to ensure there aren't false crashes from Xcode development.

• If your app has background capabilites, ensure that you are checking that the app is not in the background prior to calling lifecycleStart.

• Do not delete or modify any values that the Experience Platform SDKs puts in NSUserDefaults. If these values are modified outside the SDK, the data reported will be invalid.

Collecting additional data with Lifecycle

When calling lifecycleStart:, you can optionally pass a dictionary of additional data that will be attached to the lifecycle event.

Tip: You can pass additional data to lifecycle on app launch, app resume, both, or neither.

// Objective-C
- (void) applicationWillEnterForeground:(UIApplication *)application {      
    [ACPCore lifecycleStart:@{@"state": @"appResume"}];      
}

// Swift
func applicationWillEnterForeground(_ application: UIApplication) {      
    ACPCore.lifecycleStart(["state": "appResume"])
}