iphone - Memory not releasing after popToRootViewControllerAnimated -

i using navigationcontroller in app. after push , pop view controller 3 times app crashes because of low memory. code below.

- (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions {         self.window = [[uiwindow alloc] initwithframe:[[uiscreen mainscreen] bounds]];         homepagevc *homepage = [[viewcontroller alloc] homepage = [[viewcontroller alloc] initwithnibname:@"mainview-ipad" bundle:nil];         navigationcontroller = [[uinavigationcontroller alloc] initwithrootviewcontroller:homepage];         self.window.rootviewcontroller = navigationcontroller;         [self.window makekeyandvisible];         return yes; } 

when user pushes button, send him view controller.

 -(ibaction)showmap:(id)sender  {     mapviewcontroller *mapviewcontroller = nil;     mapviewcontroller = [[mapviewcontroller alloc] initwithnibname:@"mapview-ipad" bundle:nil];     appdelegate *appdelegate = (appdelegate *)[[uiapplication sharedapplication] delegate];     [appdelegate.navigationcontroller pushviewcontroller:mapviewcontroller animated:yes];  } 

when want come rootview controller, do

-(ibaction)goback:(id)sender {     appdelegate *appdelegate = (appdelegate *)[[uiapplication sharedapplication] delegate];     [appdelegate.navigationcontroller poptorootviewcontrolleranimated:yes]; } 

now after doing few times, gradually didreceivelowmemory gets called , app crashes.

to debug more, printed memory usage in loop.

-(void) report_memory {     struct task_basic_info info;     mach_msg_type_number_t sizem = sizeof(info);     kern_return_t kerr = task_info(mach_task_self(),                                task_basic_info,                                (task_info_t)&info,                                &sizem);     if( kerr == kern_success ) {         nslog(@"memory usage: %.4lf mb", info.resident_size/1000000.0);     } else {         nslog(@"error task_info(): %s", mach_error_string(kerr));     } } 

the outputs are

when app launches    : memory usage: 137.8263 mb after showmap first time : memory usage: 206.2172 mb gone home           : memory usage: 223.6580 mb   ==> mapvc didn't release  after showmap second time: memory usage: 227.2172 mb press go home       : memory usage: 250.2172 mb   ==> mapvc didn't release  after showmap third time : app crashes 

my lowmemory written as

- (void)didreceivememorywarning {     [super didreceivememorywarning];     nslog(@"got low memory %@",[self class]); } 

to add more surprise got low memory warning both homepagevc , mapvc. if have alreay pooped out mapvc how did receive lowmemory ? , why memory consumed mapvc did not released ? using arc.

i having same problem in code (using arc) uiviewcontroller not being released after call poptorootviewcontrolleranimated:

the reason error due nstimer in uiviewcontroller. trying invalidate timer in dealloc because nstimer using target:self (i.e. retaining pointer uiviewcontroller) dealloc never being called.

to fix issue, invalidated timer in viewwilldisappear.