Unbalanced calls to begin/end appearance transitions for

Question

I read SO about another user encountering similar error, but this error is in different case.

I received this message when I added a View Controller initially:

Answer 1

As @danh suggested, my issue was that I was presenting the modal vc before the UITabBarController was ready. However, I felt uncomfortable relying on a fixed delay before presenting the view controller (from my testing, I needed to use a 0.05-0.1s delay in performSelector:withDelay:). My solution is to add a block that gets called on UITabBarController's viewDidAppear: method:

PRTabBarController.h:

@interface PRTabBarController : UITabBarController

@property (nonatomic, copy) void (^viewDidAppearBlock)(BOOL animated);

@end

PRTabBarController.m:

#import "PRTabBarController.h"

@implementation PRTabBarController

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    if (self.viewDidAppearBlock) {
        self.viewDidAppearBlock(animated);
    }
}

@end

Now in application:didFinishLaunchingWithOptions:

PRTabBarController *tabBarController = [[PRTabBarController alloc] init];

// UIWindow initialization, etc.

__weak typeof(tabBarController) weakTabBarController = tabBarController;
tabBarController.viewDidAppearBlock = ^(BOOL animated) {
    MyViewController *viewController = [MyViewController new];
    viewController.modalPresentationStyle = UIModalPresentationOverFullScreen;
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:viewController];
    [weakTabBarController.tabBarController presentViewController:navigationController animated:NO completion:nil];
    weakTabBarController.viewDidAppearBlock = nil;
};