Alex Rivera | Logout

Object was probably modified after being freed

Asked 2011-06-11T16:45:10.053
17

I am working on a project on iPhone. I am now initiating a new UIViewController from another UIViewController, and then switch between them. Here is my code.

iGreenAppDelegate *delegate = [UIApplication sharedApplication].delegate;
if(checkInViewController) {
    [checkInViewController release];
    checkInViewController = nil;
}
checkInViewController = [[CheckInViewController alloc] initWithCheckpoint:checkpoint];

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.8];
[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:[delegate window] cache:YES];
[[delegate rootTabBarController].view removeFromSuperview];
[[delegate window] addSubview:checkInViewController.view];
[UIView commitAnimations];

The Problem is the second time I initiate the UIViewController, I want to release it to avoid causing memory leak. The Debugger displays

iGreen(916,0x3f60348c) malloc: error for object 0x130350: incorrect checksum for freed object - object was probably modified after being freed. set a breakpoint in malloc_error_break to debug

This is strange because similar codes in other parts don't return such error. Moreover, I tried autorelease, but the program will immediately crash and the Debugger says I am modifying finalized layers.

I've been working on the problem for a whole night, and still confused about it.

ios memory-management autorelease
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1 Answer

1

There are a couple of things going wrong design wise in your code. First your release the checkInViewController without removing its view from its superview (if any), then you remove the rootTabBarController's view from its superview, without doing anything to the controller itself, and you don't add the checkInViewController to the rootTabBarController or the rootViewController property of the window, so it's in the air (just retained by your current object). What happens when this (current) object gets deallocated but the view of the checkInViewController stays put (retained by) on the window?

If you release your checkInViewController but its view is still retained by the window, it is probably going to create some issues...

About the error, I think there's somewhere a weak reference (not retained) to your object that acts on it after it's freed.

answered 2011-06-11T18:46:13.203

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