Modal ViewController popping up without animation, bug?

Question

Sometimes when I use: [self presentViewController:viewController animated:YES completion:nil]; or even if a modal segue handles the transition, it just pops up without any transition, making it look ugly. Whilst rare, when this does happen, every single modal VC does the same regardless of where/how it's called. When I restart the app the issue goes and that's it, it won't happen again for some time. Something which is odd though, there is a transition when dismissing the VC. Is this a bug?

Thanks for the help,
Regards,
Mike

Update: I think I've found the cause. This bug effects most modal VC's and all Segue modal VC's when ever I present my tutorial view like this:

    [tableView deselectRowAtIndexPath:indexPath animated:NO];
    TutorialViewController *tutPopUp = [[TutorialViewController alloc] init];
    self.tabBarController.modalPresentationStyle = UIModalPresentationCurrentContext;
    [self presentModalViewController:tutPopUp animated:NO];

I think the issue is with self.tabBarController.modalPresentationStyle = UIModalPresentationCurrentContext; which effects the entire tab bar. What is the default value so I can set is back once I've loaded this particular VC?

Answered: After doing some reading of the Apple Docs I discovered that the default modalPresentationStyle is UIModalPresentationFullScreen so setting it to thus after using another presentationStyle, fixed it.

Daddy · Accepted Answer · 2013-05-16 12:42:26Z

1

If you are experiencing this on device I would imagine that there is some intensive CPU task being performed which is causing blocking and stuttering on the main thread. If it's on simulator your Mac might just be overburdened at that moment.

One thing you say makes me wonder about your memory management. You say that if you quit the app the issue goes away for awhile. Makes me think you have a memory leak which is affecting performance. Are you using ARC?

Because you're explicitly calling for animation there's no reason why it would display without it on a UIKit level.

answered May 16, 2013 at 12:42

Daddy

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6 Comments

Mackey18 Over a year ago

Hi, thanks for the answer. Yes I'm using ARC. As for overloading the CPU, it definitely doesn't feel like that. While I do do some calculations, they are minimal, and there is 0 delay between me pressing a button and the VC popping up, which I don't think would be the case if the CPU was overloaded. The app is very responsive too, and often I can be using the app for ages without ever experiencing the bug.

Mackey18 Over a year ago

Hi please have a look at my edit to the original post. Think I've found out the problem, just a little unsure on the fix.

Daddy Over a year ago

Cool, glad you found it. In the code you posted, the animation argument is set to NO, is that a typo, or is that what is somehow changing the presentationCurrentContext for the rest of your app?

Mackey18 Over a year ago

I don't think setting the argument makes a difference either way as UIModalPresentationCurrentContext has no animation (that's why I used it, so I could create my own custom animation on the view). The reason why the entire application stopped showing modal transitions was because any Modal VC that was part of my TabBarController hierarchy had it's modalPresentationStyle set to UIModalPresentationCurrentContext if that makes sense. That was thanks to this line of code: self.tabBarController.modalPresentationStyle = UIModalPresentationCurrentContext;

Daddy Over a year ago

cool, in that case you should mark your own answer. thanks for the vote :-)

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Mackey18 · Accepted Answer · 2013-05-16 14:20:51Z

1

The Issue lies here in some code which I used to display another VC elsewhere in my app:

    [tableView deselectRowAtIndexPath:indexPath animated:NO];
    TutorialViewController *tutPopUp = [[TutorialViewController alloc] init];
    self.tabBarController.modalPresentationStyle = UIModalPresentationCurrentContext;
    [self presentModalViewController:tutPopUp animated:NO];

The issue is specifically here: self.tabBarController.modalPresentationStyle = UIModalPresentationCurrentContext; because this effects the entire tab bar in my app and changes the presentation style to one with no animation. I discovered that the default modalPresentationStyle is UIModalPresentationFullScreen so setting it to thus after using another presentationStyle, fixed my issue.

edited May 16, 2013 at 14:20

answered May 16, 2013 at 13:48

Mackey18

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