Objective-c deallocated when opening a new form?

Question

Objective-C

Good afternoon.
A memory error occurs while the application is running.
[5133:307051] *** -[DeclarantController retain]: message sent to deallocated instance 0x7f9e53d22b50 I

open the form after requesting data on a background thread.

dispatch_async(dispatch_get_main_queue(), ^{
                        DeclarantController *viewController = [self.storyboard instantiateViewControllerWithIdentifier:@"DeclarantController"];
                        viewController.consultData = self.consultData;
                        viewController.parentView = self;
                        [self.navigationController pushViewController:viewController animated:YES];
                    });

I simplified the controller, but the error pops up if you put a call to the getDeclarantKind method in viewDidLoad. If commented out, no error occurs. The error occurs even with an empty method.

@implementation DeclarantController : BaseController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self tableColor];
    [self getDeclarantKind];
}

-(NSMutableArray*)getDeclarantKind
{

}
@end

If you just go through the forms of the application, then there are no errors. An error occurs with the following algorithm:
1. Form A opens, it has a button with a transition to form B
2. Form B opens on it, an API request from the site in the background process. If the answer came, form C opens
3. Form C works fine
4. Go back with a swipe to form B and then swipe to form A
5. Repeat steps 1-3. The form opens
6. Go back with a swipe to form B and then swipe to form A
7. Repeat steps 1-3. Form C opens but the buttons slide. After clicking on any area of ​​the screen, an error occurs in main.m

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

Thread 1: EXC_BREAKPOINT (code=EXC_I386_BPT, subcode=0x0)
The most incomprehensible thing is why the error only works on the 3rd pass. The first 2 work. And if you remove [self getDeclarantKind]; that too the form is rendered and works normally.