Is it possible to push a View Controller with a completion block?

Question

UINavigationController's documentation contains no pushViewController methods with a completion: parameter.

I got ur question but there is no way while push but present will have one like u expect or else u can do it didappear of pushed viewController — CoolMonster, Feb 13 '14 at 04:16

score 65 · Answer 1 · edited Apr 26 '19 at 00:50

65

The better solution would be wrapping the push animation by an CATransaction and set the completionBlock. There's no need to deal with timings.

[CATransaction begin];
[CATransaction setCompletionBlock:^{
    //whatever you want to do after the push
}];
[[self navigationController] pushViewController:viewController animated:YES];
[CATransaction commit];

edited Apr 26 '19 at 00:50

MrHappyAsthma

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answered May 21 '14 at 08:52

justMartin

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This is the best answer!! – sabadow Mar 04 '15 at 11:37
1

At least using "slow animations" suggests that this isn't the right approach. – tcurdt Jun 15 '16 at 13:44
What about Swift 4? I couldn't find `CATransaction.begin()` method. – Danh Huynh Oct 28 '17 at 08:41
Also didn't work for me. Completion block is being executed before the animation has ended. – Kai Aug 14 '18 at 11:04

score 19 · Answer 2 · edited Jan 05 '18 at 15:13

19

justMartin's answer worked great for me. For those new to using swift API:

CATransaction.begin()
navigationController?.pushViewController(viewController, animated: true)
CATransaction.setCompletionBlock({ 
    //your post animation logic
})
CATransaction.commit()

edited Jan 05 '18 at 15:13

Fattie

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answered Mar 25 '17 at 13:44

Ishaan Sejwal

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Thanks, great tip – spnkr Apr 09 '19 at 14:38
This seems to fail for me in case there is an animation that is started off as soon as the new viewcontroller loads. For example an activity indicator. I ended up creating properties in the new view controller and setting them before pushing, instead of trying to call a method in the new view controller from the old view controller once it is pushed. – humblePilgrim Jun 08 '19 at 05:20

score 14 · Answer 3 · answered Jan 05 '18 at 21:01

Solution with CATransaction is great but there is another way to do that. You can make your controller a delegate of UINavigationController and implement didShowViewController method:

class FooBarController: UIViewController, UINavigationControllerDelegate {
  func viewDidLoad() {
    self.navigationController?.delegate = self
  }

  func navigationController(navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool) {
    // your awesome completion code here 
  }
}

This approach can be more convenient for your task

score 2 · Answer 4 · answered Feb 13 '14 at 03:54

Not sure if I understand correctly, but I pushed a view controller in a completion block as follows. In a table view controller, added the following line to the header file:

typedef void(^myCompletion)(BOOL);

Then in the class itself, added the following method:

-(void) myMethod:(myCompletion) compblock
{
    compblock(YES);
}

Now in didSelectRowAtIndexPath, I called myMethod and in the completion block, pushed a view controller.

[self myMethod:^(BOOL finished) {
    if(finished){
        dispatch_async(dispatch_get_main_queue(), ^{
            DVSecondTableViewController *vc = [[DVSecondTableViewController alloc] init];
            [self.navigationController pushViewController:vc animated:YES];
        });
    }
}];

I'm not sure if it's okay to push view controllers outside of the main thread, so I embedded that call in a dispatch_async().

the OP is asking how to send completion block to push ,not push the viewController from completion block. Just like presentViewController has completion block. — santhu, Feb 13 '14 at 04:41

score 1 · Answer 5 · answered Aug 23 '18 at 07:03

Try using -[UIViewControllerTransitionCoordinator animateAlongsideTransitionInView:animation:completion:]:

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if (!self.isPushing) {
        self.pushing = YES;
        [super pushViewController:viewController animated:animated];
        if (!self.transitionCoordinator) {
            self.pushing = NO;
        } else {
            [self.transitionCoordinator animateAlongsideTransition:nil completion:^(id<UIViewControllerTransitionCoordinatorContext> context) {
                self.pushing = NO;
            }];
        }
    }
}

santhu · Accepted Answer · 2015-05-22T17:27:19.437

-9

I would go with @justMartin's answer . But below is another approach.

push animation take 0.3 seconds.So, if you want to run some function here after completion use performSelector after 0.3 seconds of delay.

[self performSelector:@selector(completedPushing:) withObject:nil afterDelay:.3];

OR
After pushing the new viewController onto navigation stack,the old viewController view is removed from view hierarchy.so this results in call of viewDidDisappear on old ViewController.You can write your completion code there. don't forget to call super at some point of implementation of viewDidDisappear.

edited May 22 '15 at 17:27

answered Feb 13 '14 at 04:56

santhu

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1

You can't say that for sure. Someone's iDevice could be running slowly, thus the animation may take longer. – Supertecnoboff Nov 05 '15 at 22:14
The `performSelector:withObject:afterDelay:` suggestion isn't so great but the `viewDidDisappear` trick worked great for me even when it's a modal view controller that's being dismissed. Thanks for that – Adil Hussain May 02 '20 at 09:32
this is an example of how things not should be done – NMaks Feb 07 '23 at 08:49

Is it possible to push a View Controller with a completion block?

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