iOS app launch due to NSUserActivity. How do access that object?

Question

So testing some ios9 beta features as of now, but NSUserActivity class has been out for a while, which is used in handoff.

Basically this is it. When app launches doe to NSUserActivity, I can see that this the launchOptions has a key set.

    NSDictionary *userActivityKey = [launchOptions objectForKey:UIApplicationLaunchOptionsUserActivityDictionaryKey]; 

Basically the method never gets called.

- (BOOL)application:(UIApplication *)application continueUserActivity:(NSUserActivity *)userActivity restorationHandler:(void(^)(NSArray * __nullable restorableObjects))restorationHandler 

This makes sense as the app is just being opened due to the activity. But what is puzzling me is this.

When I check the launchOptions, I am not able access the NSUserActivity. Apparently the OS creates that object for you??

Did any of you guys deal with this?

Answer 1

You shouldn't be doing any of that. You should return YES from -(BOOL)application:didFinishLaunchingWithOptions:, then -(BOOL)application:continueUserActivity:restorationHandler will also be called. Apple docs say:

NO if the app cannot handle the URL resource or continue a user activity, otherwise return YES.

Answer 2

I used a UIAlertView to get a description of the launchOptions when coming from an NSUserActivity:

NSDictionary *userActivityDictionary = [launchOptions objectForKey:UIApplicationLaunchOptionsUserActivityDictionaryKey]; UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"alert"                                                     message:[userActivityDictionary description]                                                    delegate:nil                                           cancelButtonTitle:@"Okay"                                           otherButtonTitles:nil]; [alertView show]; 

Apparently, this dictionary comes with a couple keys that I cannot seem to find documentation for:

UIApplicationLaunchOptionsUserActivityIdentifierKey UIApplicationLaunchOptionsUserActivityKey UIApplicationLaunchOptionsUserActivityTypeKey // there is documentation for this key 

It seems the NSUserActivity object is inside this dictionary, but it may not be good from Apple's point of view (or it may break if Apple decides to change things), to try to access this object (e.g., possibly looping through the dictionary keys and looking for an NSUserActivity object).

**** Solution ****

EDIT: Here's some implementation on how to access the NSUserActivity object from launchOptions:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {     NSDictionary *userActivityDictionary = [launchOptions objectForKey:UIApplicationLaunchOptionsUserActivityDictionaryKey];     if (userActivityDictionary) {         [userActivityDictionary enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {                 if ([obj isKindOfClass:[NSUserActivity class]]) {                     NSLog(@"found NSUserActivity object!");                 }             }];     } } 

Using this method, you don't need to know the value of the undocumented key, UIApplicationLaunchOptionsUserActivityKey.

If you're uncomfortable with the solution above, another method may be to catch the NSUserActivity object when your app enters this method,

- (BOOL)application:continueUserActivity:restorationHandler: 

Then, set this user activity as a property of your AppDelegate for later retrieval.

Note: I was able to verify that the method above is called on a cold app launch while testing Core Spotlight (iOS 9 feature).