Unrecognized Selector with OHGridView - iphone

I downloaded the OHGridView hoping that it was the answer to all my problems.
https://github.com/AliSoftware/OHGridView
I did all that it said to do (add the class files, add the code, and change a few other things).
I went to build it and it crashed. I realized the lines of code why it was crashing:
((OHGridView *)self.view).rowHeight = 100;
((OHGridView *)self.view).columnsCount = 2;
Error from Console:
`-[UIView setRowHeight:]: unrecognized selector sent to instance 0x4b55110
2011-02-20 09:01:16.906 TableView[14358:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIView setRowHeight:]: unrecognized selector sent to instance 0x4b55110'
*** Call stack at first throw:
(
0 CoreFoundation 0x00e4dbe9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x00fa25c2 objc_exception_throw + 47
2 CoreFoundation 0x00e4f6fb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x00dbf366 ___forwarding___ + 966
4 CoreFoundation 0x00dbef22 _CF_forwarding_prep_0 + 50
5 TableView 0x00004232 -[DetailViewController viewDidLoad] + 831
6 UIKit 0x0037165e -[UIViewController view] + 179
7 UIKit 0x0036fa57 -[UIViewController contentScrollView] + 42
8 UIKit 0x00380201 -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 48
9 UIKit 0x0037e831 -[UINavigationController _layoutViewController:] + 43
10 UIKit 0x0037fa86 -[UINavigationController _startTransition:fromViewController:toViewController:] + 326
11 UIKit 0x0037a606 -[UINavigationController _startDeferredTransitionIfNeeded] + 266
12 UIKit 0x0038183e -[UINavigationController pushViewController:transition:forceImmediate:] + 932
13 UIKit 0x0037a4a0 -[UINavigationController pushViewController:animated:] + 62
14 TableView 0x00002e4f -[RootViewController tableView:didSelectRowAtIndexPath:] + 681
15 UIKit 0x00339794 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1140
16 UIKit 0x0032fd50 -[UITableView _userSelectRowAtPendingSelectionIndexPath:] + 219
17 Foundation 0x000427f6 __NSFireDelayedPerform + 441
18 CoreFoundation 0x00e2efe3 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19
19 CoreFoundation 0x00e30594 __CFRunLoopDoTimer + 1220
20 CoreFoundation 0x00d8ccc9 __CFRunLoopRun + 1817
21 CoreFoundation 0x00d8c240 CFRunLoopRunSpecific + 208
22 CoreFoundation 0x00d8c161 CFRunLoopRunInMode + 97
23 GraphicsServices 0x016ef268 GSEventRunModal + 217
24 GraphicsServices 0x016ef32d GSEventRun + 115
25 UIKit 0x002d242e UIApplicationMain + 1160
26 TableView 0x00001abc main + 102
27 TableView 0x00001a4d start + 53
)
terminate called after throwing an instance of 'NSException`
I removed them and it loaded fine but I didn't see any content.
Please help,
thanks.

I did a clone of the repository just now and then did a build and run of his example project without making any changes to the code. It ran without any warnings or errors.
You'll need to check your code wherever you made changes.
update after your comment
Unrecognized Selector often means that you have a capitalization error or that your code isn't the kind of object that you think it is.
For example: I can get almost the same error that you get if I try to call the setRowHeight: directly against a OHGridView object instead of the view property of the object, like this
((OHGridView*)self).rowHeight = 100;
((OHGridView*)self).columnsCount = 2;
So, I would check your code to make sure that your object is an OHGridView and that you are setting the rowHeight property of the view of the OHGridView.

Related

SIGABRT Error on Button Click xcode

I am having a strange problem in xcode. i created a button in xib and connected to a function. I am printing the message inside the function. That's all, when i click the button i get the following error. I tried clean and deleted app from my simulator.
-(IBAction)languageSelection:(id)sender is my function name
-[NSCFString languageSelection:]: unrecognized selector sent to instance 0x713cd40
2012-05-03 15:14:35.055 Example[33420:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFString languageSelection:]: unrecognized selector sent to instance 0x713cd40'
*** Call stack at first throw:
(
0 CoreFoundation 0x02966919 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x02ab45de objc_exception_throw + 47
2 CoreFoundation 0x0296842b -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x028d8116 ___forwarding___ + 966
4 CoreFoundation 0x028d7cd2 _CF_forwarding_prep_0 + 50
5 UIKit 0x005ece14 -[UIApplication sendAction:to:from:forEvent:] + 119
6 UIKit 0x006766c8 -[UIControl sendAction:to:forEvent:] + 67
7 UIKit 0x00678b4a -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527
8 UIKit 0x006776f7 -[UIControl touchesEnded:withEvent:] + 458
9 UIKit 0x006102ff -[UIWindow _sendTouchesForEvent:] + 567
10 UIKit 0x005f21ec -[UIApplication sendEvent:] + 447
11 UIKit 0x005f6ac4 _UIApplicationHandleEvent + 7495
12 GraphicsServices 0x02dedafa PurpleEventCallback + 1578
13 CoreFoundation 0x02947dc4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
14 CoreFoundation 0x028a8737 __CFRunLoopDoSource1 + 215
15 CoreFoundation 0x028a59c3 __CFRunLoopRun + 979
16 CoreFoundation 0x028a5280 CFRunLoopRunSpecific + 208
17 CoreFoundation 0x028a51a1 CFRunLoopRunInMode + 97
18 GraphicsServices 0x02dec2c8 GSEventRunModal + 217
19 GraphicsServices 0x02dec38d GSEventRun + 115
20 UIKit 0x005fab58 UIApplicationMain + 1160
21 Example 0x000023c9 main + 121
22 Example 0x00002345 start + 53
)
terminate called after throwing an instance of 'NSException'
this is perhaps you are trying to call a method languageSelection with object that is infact string, but you have passed into another object which has languageSelection method.
this is because you think the object is what you want but the pointer passed the allocated memory to string and hence it will work as string. when you try to call method it crashes because it didn't find the method in string. check your object type just before u use it anywhere

Unrecognized selector sent to instance (self.navigationController.toolbar)

I've been banging my head against the wall for the past 2 days with it - and I need help.
In my controller, I have this code:
- (void)viewDidLoad {
[super viewDidLoad];
self.navigationController.toolbar.barStyle = UIBarStyleBlack;
[self.navigationController setToolbarHidden:NO];
... // the rest of initialisation goes here
}
This controller presents details of one item selected from the list. Controller displaying a list of items does pushViewControllerAnimated on this controller to display details of the item selected by the user.
This works fine on the first execution, however when the user presses back button - and then selects another (or even the same) item from the list, line [self.navigationController setToolbarHidden:NO] causes SIGABRT with this stack trace:
2011-11-04 10:24:21.423 OOKL[32026:10403] -[NSCFNumber view]: unrecognized selector sent to instance 0x69db0e0
2011-11-04 10:24:21.426 OOKL[32026:10403] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFNumber view]: unrecognized selector sent to instance 0x69db0e0'
*** Call stack at first throw:
(
0 CoreFoundation 0x019875a9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x01adb313 objc_exception_throw + 44
2 CoreFoundation 0x019890bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x018f8966 ___forwarding___ + 966
4 CoreFoundation 0x018f8522 _CF_forwarding_prep_0 + 50
5 UIKit 0x0063223e -[UIToolbar setItems:animated:] + 1554
6 UIKit 0x005f8ccb -[UIViewController(UINavigationControllerContextualToolbar) setToolbarItems:] + 49
7 OOKL 0x0003df87 -[OOExplorerObjectDetailController setUpToolbarForExplore] + 1335
8 OOKL 0x0003eb2b -[OOExplorerObjectDetailController viewDidLoad] + 2043
9 UIKit 0x005fd089 -[UIViewController view] + 179
10 UIKit 0x005fb482 -[UIViewController contentScrollView] + 42
11 UIKit 0x0060bf25 -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 48
12 UIKit 0x0060a555 -[UINavigationController _layoutViewController:] + 43
13 UIKit 0x0060b870 -[UINavigationController _startTransition:fromViewController:toViewController:] + 524
14 UIKit 0x0060632a -[UINavigationController _startDeferredTransitionIfNeeded] + 266
15 UIKit 0x0060d562 -[UINavigationController pushViewController:transition:forceImmediate:] + 932
16 UIKit 0x006061c4 -[UINavigationController pushViewController:animated:] + 62
17 OOKL 0x0002ed8b -[OOExploreController showObjectDetailControllerWithObject:] + 571
18 OOKL 0x0002da1c -[OOExploreController parserDidFinish:] + 316
19 OOKL 0x00021c13 -[OOXMLParser parserDidEndDocument:] + 99
20 Foundation 0x00385717 _endDocument + 95
21 libxml2.2.dylib 0x02ad4215 xmlParseChunk + 7380
22 Foundation 0x0038615a -[NSXMLParser parse] + 321
23 OOKL 0x00021893 -[OOXMLParser parseString:] + 339
24 OOKL 0x0002d8d5 -[OOExploreController parseXml:] + 165
25 OOKL 0x0002d81f -[OOExploreController requestDidFinishLoading:] + 79
26 OOKL 0x00011cba -[OOSharedSeverController connectionDidFinishLoading:] + 298
27 Foundation 0x002ef112 -[NSURLConnection(NSURLConnectionReallyInternal) sendDidFinishLoading] + 108
28 Foundation 0x002ef06b _NSURLConnectionDidFinishLoading + 133
29 CFNetwork 0x013cd48e _ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE + 220
30 CFNetwork 0x014986e1 _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 293
31 CFNetwork 0x013c3c80 _ZN19URLConnectionClient13processEventsEv + 100
32 CFNetwork 0x013c3acf _ZN17MultiplexerSource7performEv + 251
33 CoreFoundation 0x019688ff __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
34 CoreFoundation 0x018c688b __CFRunLoopDoSources0 + 571
35 CoreFoundation 0x018c5d86 __CFRunLoopRun + 470
36 CoreFoundation 0x018c5840 CFRunLoopRunSpecific + 208
37 CoreFoundation 0x018c5761 CFRunLoopRunInMode + 97
38 GraphicsServices 0x01e601c4 GSEventRunModal + 217
39 GraphicsServices 0x01e60289 GSEventRun + 115
40 UIKit 0x0055bc93 UIApplicationMain + 1160
41 OOKL 0x00002d09 main + 121
42 OOKL 0x00002c85 start + 53
)
I thought, maybe, I should setup self.toolbarItems first before making the toolbar visible - but then I get this same error when I do
self.toolbarItems = [NSArray ...]
I'm desperate now - any help is appreciated.
Edit: Now for some reason I'm getting EXC_BAD_ACCESS instead of SIGABRT - in the same place - and no stack trace is produced at all.
As the stack trace tells:
-[NSCFNumber view]: unrecognized selector sent to instance 0x69db0e0
You are accidentally overreleasing something that is leading to this message sent to some dangling pointer (reference to some junk).
Check if you are releasing your navigationController, ViewController or anything where your workflow begins.

Error in dismissing a modal view controller

I have encountered application termination while dismissing a modal view controller.
-[NSCFString window]: unrecognized selector sent to instance 0x6337dc0
2011-06-03 13:26:37.980 Tuscany[19657:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFString window]: unrecognized selector sent to instance 0x6337dc0'
*** Call stack at first throw:
(
0 CoreFoundation 0x016ffbe9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x018545c2 objc_exception_throw + 47
2 CoreFoundation 0x017016fb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x01671366 ___forwarding___ + 966
4 CoreFoundation 0x01670f22 _CF_forwarding_prep_0 + 50
5 UIKit 0x003f4024 -[UIViewController viewControllerForRotation] + 81
6 UIKit 0x003ee8ab -[UIViewController shouldWindowUseOnePartInterfaceRotationAnimation:] + 34
7 UIKit 0x00368dd5 -[UIWindow _clientsForRotation] + 350
8 UIKit 0x0036b87b -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:] + 141
9 UIKit 0x005eb948 -[UIWindowController transition:fromViewController:toViewController:target:didEndSelector:] + 1053
10 UIKit 0x003f7682 -[UIViewController _dismissModalViewControllerWithTransition:from:] + 2075
11 UIKit 0x003f4324 -[UIViewController dismissModalViewControllerWithTransition:] + 579
12 Foundation 0x000c37f6 __NSFireDelayedPerform + 441
13 CoreFoundation 0x016e0fe3 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19
14 CoreFoundation 0x016e2594 __CFRunLoopDoTimer + 1220
15 CoreFoundation 0x0163ecc9 __CFRunLoopRun + 1817
16 CoreFoundation 0x0163e240 CFRunLoopRunSpecific + 208
17 CoreFoundation 0x0163e161 CFRunLoopRunInMode + 97
18 GraphicsServices 0x01d88268 GSEventRunModal + 217
19 GraphicsServices 0x01d8832d GSEventRun + 115
20 UIKit 0x0035342e UIApplicationMain + 1160
21 Tuscany 0x00002878 main + 102
22 Tuscany 0x00002809 start + 53
)
terminate called after throwing an instance of 'NSException'
Above is the crash log. Please help.
Thanks in advance.
From you log it seems that you are calling window on an NSCFString. NSCFString does not have a window selector, and the compiler would complain if you try and do so, so it is likely that you are sending that message to a deallocated object (imagine that a new object has been allocated where another one was previously), or you are messing with casts.
In case you suspect that you are sending the message to a deallocated object, enable NSZombies.
Without seeing the code, it is not possible to help you further, though.

unrecognized selector sent to instance

I have added a tabbarcontroller on window and a button on view respective to first tab.
As I run the app and press the button, the app is crashing with this msg:
2011-05-20 18:56:46.258 FeatureList[3395:207] -[UIViewController barButtonPressed:]: unrecognized selector sent to instance 0x4b22520
2011-05-20 18:56:46.262 FeatureList[3395:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIViewController barButtonPressed:]: unrecognized selector sent to instance 0x4b22520'
*** Call stack at first throw:
(
0 CoreFoundation 0x00da9be9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x00efe5c2 objc_exception_throw + 47
2 CoreFoundation 0x00dab6fb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x00d1b366 ___forwarding___ + 966
4 CoreFoundation 0x00d1af22 _CF_forwarding_prep_0 + 50
5 UIKit 0x002b2a6e -[UIApplication sendAction:to:from:forEvent:] + 119
6 UIKit 0x003411b5 -[UIControl sendAction:to:forEvent:] + 67
7 UIKit 0x00343647 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527
8 UIKit 0x003421f4 -[UIControl touchesEnded:withEvent:] + 458
9 UIKit 0x002d70d1 -[UIWindow _sendTouchesForEvent:] + 567
10 UIKit 0x002b837a -[UIApplication sendEvent:] + 447
11 UIKit 0x002bd732 _UIApplicationHandleEvent + 7576
12 GraphicsServices 0x016dfa36 PurpleEventCallback + 1550
13 CoreFoundation 0x00d8b064 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
14 CoreFoundation 0x00ceb6f7 __CFRunLoopDoSource1 + 215
15 CoreFoundation 0x00ce8983 __CFRunLoopRun + 979
16 CoreFoundation 0x00ce8240 CFRunLoopRunSpecific + 208
17 CoreFoundation 0x00ce8161 CFRunLoopRunInMode + 97
18 GraphicsServices 0x016de268 GSEventRunModal + 217
19 GraphicsServices 0x016de32d GSEventRun + 115
20 UIKit 0x002c142e UIApplicationMain + 1160
21 FeatureList 0x000024fc main + 102
22 FeatureList 0x0000248d start + 53
23 ??? 0x00000001 0x0 + 1
)
terminate called after throwing an instance of 'NSException'
Program received signal: “SIGABRT”.
kill
quit
The Debugger has exited with status 0.(gdb)
This happens when you try to call a method that doesn't exist. It looks like you've set up your button to send a message to the view controller (barButtonPressed:), but you may not have implemented the method if your view controller. Or you may have misspelled the method name or not included the argument in the method implementation.
Post your view controller code.
It looks like the button is trying to call barButtonPressed: on the view controller, but that method doesn't exist. Are you sure you don't get warnings during compilation regarding missing methods? My guess is you're not setting the view controller class correctly in a nib file.
Have you implemented barButtonPressed:? Are you sure you need the colon? Try barButtonPressed as the selector name instead.
This is an old question, but I think I know what happened. Notice how the error message says UIViewController instead of TodayDeal; he needed to change the Xib's file owner from a default UIViewController to TodayDeal

unrecognized selector sent to instance. Method being called for random objects

Ok, so this has me completely stumped just like the guy here with the exact problem.
I have a UITableView with some rows in a view controller which supports autorotation and sometimes, if i rotate the phone, i get "EXC_BAD_ACCESS" and sometimes i get SIGABRT with a stack trace like:
2010-11-19 16:51:05.634 [2306:307] -[CABasicAnimation numberOfSectionsInTableView:]: unrecognized selector sent to instance 0x58207d0
2010-11-19 16:51:05.688 [2306:307] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CABasicAnimation numberOfSectionsInTableView:]: unrecognized selector sent to instance 0x58207d0'
*** Call stack at first throw:
(
0 CoreFoundation 0x344aaed3 __exceptionPreprocess + 114
1 libobjc.A.dylib 0x33975811 objc_exception_throw + 24
2 CoreFoundation 0x344ac683 -[NSObject(NSObject) doesNotRecognizeSelector:] + 102
3 CoreFoundation 0x344541d9 ___forwarding___ + 508
4 CoreFoundation 0x34453f90 _CF_forwarding_prep_0 + 48
5 UIKit 0x31b20717 -[UITableViewRowData(UITableViewRowDataPrivate) _updateNumSections] + 66
6 UIKit 0x31b20677 -[UITableViewRowData invalidateAllSections] + 50
7 UIKit 0x31b2048d -[UITableView(_UITableViewPrivate) _updateRowData] + 64
8 UIKit 0x31b22941 -[UITableView(_UITableViewPrivate) _ensureRowDataIsLoaded] + 24
9 UIKit 0x31b22909 -[UITableView numberOfSections] + 16
10 UIKit 0x31bd114f -[UISearchDisplayController _updateNoSearchResultsMessageVisiblity] + 54
11 UIKit 0x31cfbef7 -[UISearchDisplayController windowWillAnimateRotation:] + 478
12 Foundation 0x3325d6b3 _nsnote_callback + 142
13 CoreFoundation 0x34431713 __CFXNotificationPost_old + 402
14 CoreFoundation 0x344313b3 _CFXNotificationPostNotification + 118
15 Foundation 0x3324cdb7 -[NSNotificationCenter postNotificationName:object:userInfo:] + 70
16 UIKit 0x31b5dbb7 -[UIWindow _setRotatableClient:toOrientation:duration:force:] + 3114
17 UIKit 0x31b64013 -[UIWindow _setRotatableViewOrientation:duration:force:] + 50
18 UIKit 0x31b39a0f -[UIWindow _updateToInterfaceOrientation:duration:force:] + 74
19 UIKit 0x31b39be9 -[UIWindow _updateInterfaceOrientationFromDeviceOrientation:] + 112
20 UIKit 0x31b39b15 -[UIWindow _handleDeviceOrientationChange:] + 88
21 Foundation 0x3325d6b3 _nsnote_callback + 142
22 CoreFoundation 0x34431713 __CFXNotificationPost_old + 402
23 CoreFoundation 0x344313b3 _CFXNotificationPostNotification + 118
24 Foundation 0x3324cdb7 -[NSNotificationCenter postNotificationName:object:userInfo:] + 70
25 UIKit 0x31b0d0ed -[UIDevice setOrientation:animated:] + 144
26 UIKit 0x31b2a51b -[UIApplication handleEvent:withNewEvent:] + 2738
27 UIKit 0x31b29901 -[UIApplication sendEvent:] + 44
28 UIKit 0x31b29337 _UIApplicationHandleEvent + 5110
29 GraphicsServices 0x3026c04b PurpleEventCallback + 666
30 CoreFoundation 0x3443fce3 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 26
31 CoreFoundation 0x3443fca7 __CFRunLoopDoSource1 + 166
32 CoreFoundation 0x3443256d __CFRunLoopRun + 520
33 CoreFoundation 0x34432277 CFRunLoopRunSpecific + 230
34 CoreFoundation 0x3443217f CFRunLoopRunInMode + 58
35 GraphicsServices 0x3026b5f3 GSEventRunModal + 114
36 GraphicsServices 0x3026b69f GSEventRun + 62
37 UIKit 0x31ad0123 -[UIApplication _run] + 402
38 UIKit 0x31ace12f UIApplicationMain + 670
39 App 0x0000285f main + 70
40 App 0x00002814 start + 40
)
terminate called after throwing an instance of 'NSException'
Program received signal: “SIGABRT”.
In this case it is CABasicAnimation on which numberOfSectionsInTableView is being called but sometimes there are class names like NSMachPort which i have never heard of. Also, the method being called numberOfSectionsInTableView remains the same with the class names changing to always give a doesNotRecognizeSelector exception.
Also this problem only happens when i try to rotate the device. Whenever i get a stack trace like above, there are all system functions which makes it difficult to debug.
Really need some expert advice on this. Please read the forum mentioned above to be clear about the issue.
Whoa! I thought i knew NSZombies enough but i was wrong!
I enabled NSZombies which led me to:
*** -[ContactsViewController numberOfSectionsInTableView:]: message sent to deallocated instance 0x88dafa0
Doing "po 0x88dafa0" wont work because that object's memory was already freed.
Some more Googling led me to this where the author describes how to find freed/deallocated objects. We just have to set MallocStackLoggingNoCompact to 1 in the Variables to be set in the environment along with NSZombieEnabled.
The output i got with the info malloc-history 0xf270740 command had a line:
-[VoicePlayController actionSheet:clickedButtonAtIndex:] at /Users/Documents/Xcode Projects/Classes/VoicePlayController.m:454
The code on that line is:
contactsViewController = [[ContactsViewController alloc] initWithNibName:#"ContactsViewController" bundle:nil];
I moved the [contactsViewController release]; line to dealloc method instead of immediately after [self.navigationController presentModalViewController:contactsViewController animated:YES]; and the problem is gone!
Start with enabling NSZombies. What it sounds like is you are over-releasing an object.