[jira] [Commented] (CB-1578) App crash (while stopping) caused by an unregistered notification handler in CDVConnection

["Becky Gibson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CB-1578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13469748#comment-13469748 ] 

Becky Gibson commented on CB-1578:
----------------------------------

Took your information and did the necessary clean up of notifications in the appropriate dealloc.   Patch is here: https://github.com/becka11y/incubator-cordova-ios/tree/cb1578

Will check in early next week. Shaz did the original work on this and if he is back from leave next week I'd like to give him a chance to review.
                
> App crash (while stopping) caused by an unregistered notification handler in CDVConnection
> ------------------------------------------------------------------------------------------
>
>                 Key: CB-1578
>                 URL: https://issues.apache.org/jira/browse/CB-1578
>             Project: Apache Cordova
>          Issue Type: Bug
>          Components: iOS
>    Affects Versions: 2.0.0, 2.1.0
>         Environment: iOS, all versions
> XCode, all versions
>            Reporter: Christoph Jerolimov
>            Assignee: Shazron Abdullah
>            Priority: Critical
>
> The class {{CDVConnection}} registered itself as observer for background events {{UIApplicationDidEnterBackgroundNotification}} and {{UIApplicationWillEnterForegroundNotification}}. But it did NOT unregistered these calls, for example in the dealloc method.
> This caused in different type of errors which all ends in an app crash. If a CDVConnection instance was already removed from the memory the selectors onPause and onResume will be called on random other objects which doesn't support this selector (1) or illegal memory access!
> {code}
> # Only an example, this error calls selectors on "random memory / objects"!
> <Error>: -[CALayer onPause]: unrecognized selector sent to instance 0x1e56ac50
> {code}
> The code which register the notification could be found at the end of the file in the selector {{[CDVConnection initWithWebView:]}}.
> The versions 2.0.0 and 2.1.0 does NOT cleanup "only" the two mentioned events. Like you see in line 139:
> https://github.com/apache/incubator-cordova-ios/blob/2.0.0/CordovaLib/Classes/CDVConnection.m#L139
> https://github.com/apache/incubator-cordova-ios/blob/2.1.0/CordovaLib/Classes/CDVConnection.m#L139
> The current HEAD do additionally NOT remove the the event {{kReachabilityChangedNotification}} from line 113 which should result in another new bug in the upcoming version.
> https://github.com/apache/incubator-cordova-ios/blob/master/CordovaLib/Classes/CDVConnection.m#L113
> To fix this it's enough to add these removeObservers calls again to the dealloc method.
> {code}
> [[NSNotificationCenter defaultCenter] removeObserver:self name:kReachabilityChangedNotification object:nil];
> [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
> [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillEnterForegroundNotification object:nil];
> {code}
> In generally it's would also be possible to remove the instance in CDVPlugin for all events!? This would allow you to remove many code from many different plugins and ensure that no other plugin forget these cleanup.
> {code}
> 	[[NSNotificationCenter defaultCenter] removeObserver:self];
> {code}

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