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From "Marc Rhodes (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CB-401) Crash on iOS when taking multiple pictures
Date Fri, 06 Apr 2012 19:57:22 GMT

    [ https://issues.apache.org/jira/browse/CB-401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13248663#comment-13248663
] 

Marc Rhodes commented on CB-401:
--------------------------------

You are, of course, correct. As you noted, I managed to overlook that this was an assignment
to a property not an ivar. I appreciate your kind explanation and apologize for the unnecessary
report based on a mistake in my analysis.
                
> Crash on iOS when taking multiple pictures
> ------------------------------------------
>
>                 Key: CB-401
>                 URL: https://issues.apache.org/jira/browse/CB-401
>             Project: Apache Callback
>          Issue Type: Bug
>          Components: iOS
>    Affects Versions: 1.4.0
>         Environment: 1.4.1, 1.5.0 on iOS
> Crash on iPad (third generation)
>            Reporter: Marc Rhodes
>            Assignee: Shazron Abdullah
>            Priority: Critical
>
> We have an app that allows the user to take four pictures. It had been working fine but
we started seeing crashes when we tested on a new iPad (third generation).
> We have eliminated the crash in our application by making the following change to the
PhongeGap/Cordova code. I tested with PhoneGap 1.4.1. I'm currently upgrading to Cordova 1.5.0
but a review of {{Camera.m}}/{{CDVCamera.m}} shows only the name changes.
> Line numbers below correspond to {{CDVCamera.m}}.
> In {{CDVCamera.m}}, we found the following code around line 67:
> {code}
> if (self.pickerController == nil) 
> {
>     self.pickerController = [[[CameraPicker alloc] init] autorelease];
> }
> {code}
> We removed the autorelease message:
> {code}
> if (self.pickerController == nil) 
> {
>     self.pickerController = [[CameraPicker alloc] init];
> }
> {code}
> Our reason for doing this is that we found that {{self.pickerController}} appears to
be released in all the right places:
> * at line 220 in {{imagePickerController:didFinishPickingMediaWithInfo:}}
> {code}
> 		self.pickerController = nil;
> {code}
> * at line 251 in {{imagePickerControllerDidCancel:}}
> {code}
> 		self.pickerController = nil;
> {code}
> * at line 399 in {{dealloc}}:
> {code}
> 		self.pickerController = nil;
> {code}
> This last one may not always be necessary but should be okay since the previous releases
set the instance variable to {{nil}}. And, of course, since pickerController is a property,
setting it to {{nil}} serves to release it.
> I think both autoreleasing and explicitly releasing an object is not following the memory
management rules. Apple says:
> * [https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmRules.html]
> * Memory Management Policy
> 	** Basic Memory Management Rules
> 		*** You relinquish ownership of an object by sending it a release message or an autorelease
message.
> My thought (confirmed with an instructor at [Big Nerd Ranch|http://www.bignerdranch.com/])
is that "or" is the key word in this statement and removing the extra autorelease could certainly
prevent zombie crashes that only occur in certain circumstances.
> This issue seems like a duplicate of [CB-264|https://issues.apache.org/jira/browse/CB-264]
but since that one is resolved as "won't fix," I have submitted this new issue containing
a possible solution.

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