viewDidAppear called twice, but viewWillAppear called once

Question

I have discovered that when my program starts, in one of my viewcontrollers the order of calling is viewDidAppear, viewWillAppear, viewDidAppear.

I was not expecting the first viewDidAppear to be called. What could be causing this and how do I fix it? ATM I have a flag in viewDiDAppear to check if viewWillAppear was called, but it's a hack.

The stacktrace (which is identical in bot calls to viewDidAppear)is:

#0  0x0000509e in -[MainView viewDidAppear:] at MainView.m:497
#1  0x3097e96e in -[UINavigationController navigationTransitionView:didEndTransition:fromView:toView:]
#2  0x30af3abe in -[UINavigationTransitionView _notifyDelegateTransitionDidStopWithContext:]
#3  0x30af4930 in -[UINavigationTransitionView _navigationTransitionDidStop]
#4  0x3091af0d in -[UIViewAnimationState sendDelegateAnimationDidStop:finished:]
#5  0x3091ba9e in +[UIViewAnimationState popAnimationState]
#6  0x30af46fd in -[UINavigationTransitionView transition:fromView:toView:]
#7  0x30af3b01 in -[UINavigationTransitionView transition:toView:]
#8  0x30979f09 in -[UINavigationController _startDeferredTransitionIfNeeded]
#9  0x30a97d9c in -[UILayoutContainerView layoutSubviews]
#10 0x0040bd94 in -[CALayer layoutSublayers]
#11 0x0040bb55 in CALayerLayoutIfNeeded
#12 0x0040b3ae in CA::Context::commit_transaction
#13 0x0040b022 in CA::Transaction::commit
#14 0x308f942a in -[UIApplication _reportAppLaunchFinished]
#15 0x308fef33 in -[UIApplication handleEvent:withNewEvent:]
#16 0x308fad82 in -[UIApplication sendEvent:]
#17 0x309013e1 in _UIApplicationHandleEvent
#18 0x32046375 in PurpleEventCallback
#19 0x30245560 in CFRunLoopRunSpecific
#20 0x30244628 in CFRunLoopRunInMode
#21 0x308f930d in -[UIApplication _run]
#22 0x309021ee in UIApplicationMain
#23 0x00001e82 in main at main.m:14

can you please share your view hierarchy? What is added to window? what is the rootViewController in UINavigationController? etc — Deniz Mert Edincik, Oct 30 '10 at 20:32
Share some code. Check for a misspelling of the viewWillAppear method. — coneybeare, Jul 25 '12 at 12:38

score 1 · Answer 1 · answered Jul 31 '13 at 17:06

I just ran into a very similar problem. In my case, that was because of a bug from the ECSlidingViewController (https://github.com/edgecase/ECSlidingViewController). I just updated the code from github, solved the problem.

Using a ECSlidingViewController, on top of the uikit navigationController, made the child's viewDidAppear called twice.

score 0 · Answer 2 · answered Oct 30 '10 at 00:25

0

Put a break point in viewDidAppear, then inspect the call stack in the debugger. It will tell you what is calling the method.

answered Oct 30 '10 at 00:25

coneybeare

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I've done that, but they are both coming from main, specifically UIApplicationMain(...) – John Smith Oct 30 '10 at 00:43
Why dont you add the stack traces here. – coneybeare Oct 30 '10 at 04:10
Please add the stack traces here, yes – Fab1n Jul 25 '12 at 11:42

score 0 · Answer 3 · answered Oct 30 '10 at 03:44

When viewDidAppear is called, can you cancel another viewDidAppear in the event queue by following method ? Sometimes I use this to avoid some methods being called twice or more.

[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(viewDidAppear) object:nil];

score -1 · Answer 4 · answered Oct 30 '10 at 01:33

-1

It's very likely that you want the behavior of viewDidLoad rather than viewDidAppear - viewDidAppear can be called multiple times by your ViewController when you're not expecting it to.

answered Oct 30 '10 at 01:33

MHarrison

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No. I want the viewDidAppear. You are not answering the question I asked. Again:Why is viewDidAppear being called without a corresponding viewWillAppear? – John Smith Oct 30 '10 at 02:21

viewDidAppear called twice, but viewWillAppear called once

4 Answers4