ios - Realm must not be nil -

i updated app realm 0.9x но 2.0.x have lot of bug reports 8, 9 , 10 ios devices on crashlytics fatal exception:

fatal exception: rlmexception realm must not nil 

stack trace looks this:

rlmobjectstore.mm line 81 rlmgetobjects

rlmobject.mm line 154 +[rlmobject objectsinrealm:withpredicate:]

rlmobject.mm line 146 +[rlmobject objectsinrealm:where:args:]

rlmobject.mm line 140 +[rlmobject objectsinrealm:where:]

sessions.m line 88 +[sessions resultwithsessionswhere:]

sessions.m line 128 +[sessions activesession]

sessions.m line 102 +[sessions applaunched]

appdelegate.m line 60 -[appdelegate application:didfinishlaunchingwithoptions:]

i can't reproduce bug on debug environment. touched around 30-40% of users (not @ all), , looks old users touched.

there no realm object in method:

/**  *  create , returns realm configuration sessions database  */ +(nonnull rlmrealmconfiguration*)realmconfigurationforsessions {     rlmrealmconfiguration *config = [rlmrealmconfiguration defaultconfiguration];     // use default directory, replace filename 'sessions.realm'     config.fileurl = [nsurl                   urlwithstring:[[[config.fileurl.absolutestring stringbydeletinglastpathcomponent]                                       stringbyappendingpathcomponent:@"sessions"]                                      stringbyappendingpathextension:@"realm"]];     return config; }  +(nullable rlmrealm*)realmforconfiguration:(nullable rlmrealmconfiguration*)config {     if (!config) {         return nil;     }     nserror *error;     // open realm configuration     rlmrealm *realm = [rlmrealm realmwithconfiguration:config                                                  error:&error];     if (error) {         dlog(@"error: %@", error.localizeddescription);     }     return realm; } 

questions: 1) cause of strange issue? 2) how can handle error , nil realm value in situation?

that exception occurs in pretty straightforward case. error occurred , resulted in rlmrealm instance not being created when should have been.

with information you've provided, it's possible way you're constructing fileurl property might not succeeding in cases.

my recommendations:

• use [nsurl fileurlwithpath:] instead of [nsurl urlwithstring:]. 1 better optimized file paths opposed web urls.
• use config.fileurl.path instead of config.fileurl.absolutestring. more information why, check answer.
• for consistency's sake, use [nsurl urlbyappendingpathcomponent:] opposed [nsstring stringbyappendingpathcomponent:].

i hope helped! let me know if need additional clarification!