pushviewcontroller animation is slow/choppy

问题:

I push a ViewController which contains not too many views, UIScrollView which contains 10 views inside, I have a singleton ViewController and push it again and again without releasing and allocation again the ViewController, so all the things I do it in viewDidLoad(), and viewWillAppear(), but the animation is slow and choppy, what it could be?

回答1:

I had a problem where when UIViewController A did a pushViewController to push UIViewController B, the push animation would stop at about 25%, halt, and then slide B in the rest of the way.

This DID NOT happen on iOS 6, but as soon as I started using iOS 7 as the base SDK in XCode 5, this started happening.

The fix is that view controller B did not have a backgroundColor set on its root view (the root view is the one that is the value of viewController.view, that you typically set in loadView). Setting a backgroundColor in that root view's initializer fixed the problem.

I managed to fix this as follows:

// CASE 1: The root view for a UIViewController subclass that had a halting animation

- (id)initWithFrame:(CGRect)frame

{

     if ((self = [super initWithFrame:frame])) {

          // Do some initialization ...

          // self.backgroundColor was NOT being set

          // and animation in pushViewController was slow and stopped at 25% and paused

     }

     return self;

}

// CASE 2: HERE IS THE FIX

- (id)initWithFrame:(CGRect)frame

{

     if ((self = [super initWithFrame:frame])) {

          // Do some initialization ...

          // Set self.backgroundColor for the fix!

          // and animation in pushViewController is no longer slow and and no longer stopped at 25% and paused

          self.backgroundColor = [UIColor whiteColor]; // or some other non-clear color

     }

     return self;

}

回答2:

Only solution to this problem, never set background color of main view to clear color.

As your next view coming over the previous view, if you set background to clear color, means it is transparent, the previous view is always visible for sometime which spoil animation.

回答3:

You could start by using Instruments > Time Profiler and see if there is any part of your code that is taking longer than necessary.

You could also use the Instruments > Core Animation tool which can be used to flag parts of your screen that not drawing/animating efficiently.

If you're using an old iPhone or an original iPod - with complex screens, i've noticed some apps a bit choppy.

回答4:

I had this problem, and it was because of old code in the pushed view controller, which caused the view to "fade in", setting the alpha to 0 on viewWillAppear and setting the alpha to 1 on viewDidAppear.

I removed the old code that did this, and the push worked fine.

-(void)viewWillAppear {
    self.view.alpha = 0; //REMOVE THIS LINE
}

回答5:

My problem is I puts mass load codes in viewWillAppear. My case is

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    tableView.reloadData()
}

And I have a lot of rows, so pushViewController is laggy.

回答6:

This may be the known bug discussed in the linked an answer below. I had a similar issue and reading the answer below clarified it for me.

I've encountered the same issue today. I dug into the topic and it seems that it's related to the main runloop being asleep.

See this.