UIKeyboardWillShowNotification triggered two times on iOS 8 and only one time on iOS 7 when rotating

Question

Sébastien OP

Created Jun ’15

Replies 6

Boosts 0

Views 4.6k

Participants 2

Hi all,

From the very simple piece of code below, I have a strange behaviour difference between iOS 7 and 8 when rotating :

- On iOS 7 the keyboardWillShow and keyboardWillHide are called only one time each.

- On iOS 8 the keyboardWillShow and keyboardWillHide are called two times each.

I have created a very simple project to ensure that it was not a side effect of my main project, but it is not.

Is it a documented behaviour difference ?

Regards.

Sébastien.

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

/

}

- (void)viewWillAppear:(BOOL)animated

{

[super viewWillAppear:animated];

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(keyboardWillShow:)

name:UIKeyboardWillShowNotification

object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(keyboardWillHide:)

name:UIKeyboardWillHideNotification

object:nil];

}

-(void)keyboardWillShow:(NSNotification*)notification

{

NSLog(@"Keyboard will show");

}

-(void)keyboardWillHide:(NSNotification*)notification

{

NSLog(@"Keyboard will hide");

}

@end

Boost

Answer 1

kgellci OP

Jun ’15

Put a break point in your viewWillAppear and make sure that you are not subscribing to the same notification multiple times. I am not sure what the flow of your viewController is but I do not see where you remove the viewController as an observer from notification center.

0

Answer 2

Dex OP

Jun ’15

If you set a breakpoint in -keyboardWillShow, what do the backtraces look like for each of the two invocations?

0

Answer 3

Sébastien OP

Jun ’15

Hi,

I put a breakpoint in viewWillAppear and there is only one subscription for each notification.

I remove the notification in viewWillDisappear, I just drop it from the code pasted here.

Regards.

Sébastien.

0

Answer 4

Sébastien OP

Jun ’15

Hi Dex,

What should I look for in the backtrace ?

Regards.

Sébastien.

0

Answer 5

Dex OP

Jun ’15

Post them.

0

Answer 6

Sébastien OP

Jun ’15

Hi Dex,

Here are the backtraces for iOS 8 and iOS 7. The both are taken with the same project running in the iOS simulator (the behaviour is the same in iPad devices).

First the iOS 8.3 backtraces, two times call willHide/WillShow. Then the same on iOS 7.1, one time call willHide/WillShow

Reagards.

Sebastien.

iOS 8.3 :

---------

2015-06-19 11:49:36.674 TestKWS[12305:761940] Keyboard will hide

(lldb) bt

* thread #1: tid = 0xba054, 0x000000010fe489d0 TestKWS`-[ViewController keyboardWillHide:](self=0x00007fa84381e1d0, _cmd=0x000000010fe48ec6, notification=0x00007fa843869890) + 64 at ViewController.m:57, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1

* frame #0: 0x000000010fe489d0 TestKWS`-[ViewController keyboardWillHide:](self=0x00007fa84381e1d0, _cmd=0x000000010fe48ec6, notification=0x00007fa843869890) + 64 at ViewController.m:57

frame #1: 0x00000001106b054c CoreFoundation`__CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12

frame #2: 0x00000001105aea04 CoreFoundation`_CFXNotificationPost + 2484

frame #3: 0x000000010fed0968 Foundation`-[NSNotificationCenter postNotificationName:object:userInfo:] + 66

frame #4: 0x00000001111a0f73 UIKit`-[UIInputWindowController postStartNotifications:withInfo:] + 340

frame #5: 0x00000001111a2832 UIKit`__77-[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:]_block_invoke576 + 375

frame #6: 0x0000000110f8ab2b UIKit`-[UIInputViewAnimationStyle launchAnimation:afterStarted:completion:forHost:fromCurrentPosition:] + 190

frame #7: 0x00000001111a253d UIKit`-[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:] + 972

frame #8: 0x0000000110b5168e UIKit`+[UIView(Animation) performWithoutAnimation:] + 65

frame #9: 0x00000001111a3e09 UIKit`__69-[UIInputWindowController willRotateToInterfaceOrientation:duration:]_block_invoke + 90

frame #10: 0x000000011119f782 UIKit`-[UIInputWindowController performWithoutAppearanceCallbacks:] + 28

frame #11: 0x00000001111a3b64 UIKit`-[UIInputWindowController willRotateToInterfaceOrientation:duration:] + 1257

frame #12: 0x0000000110c1caf1 UIKit`-[UIViewController viewWillTransitionToSize:withTransitionCoordinator:] + 317

frame #13: 0x0000000110c151c8 UIKit`+[UIViewController _performWithoutDeferringTransitions:] + 101

frame #14: 0x0000000110c24ee8 UIKit`-[UIViewController(AdaptiveSizing) _window:viewWillTransitionToSize:withTransitionCoordinator:] + 886

frame #15: 0x0000000110b2a91b UIKit`-[UIWindow _rotateToBounds:withAnimator:transitionContext:] + 459

frame #16: 0x0000000110b2ccb7 UIKit`-[UIWindow _rotateWindowToOrientation:updateStatusBar:duration:skipCallbacks:] + 1741

frame #17: 0x0000000110b2d5fa UIKit`-[UIWindow _setRotatableClient:toOrientation:applyTransformToWindow:updateStatusBar:duration:force:isRotating:] + 559

frame #18: 0x0000000110b2c56e UIKit`-[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:isRotating:] + 116

frame #19: 0x0000000110df5fef UIKit`-[UITextEffectsWindow applicationWindowRotated:] + 291

frame #20: 0x00000001106b054c CoreFoundation`__CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12

frame #21: 0x00000001105aea04 CoreFoundation`_CFXNotificationPost + 2484

frame #22: 0x000000010fed0968 Foundation`-[NSNotificationCenter postNotificationName:object:userInfo:] + 66

frame #23: 0x0000000110b2c472 UIKit`-[UIWindow _setRotatableViewOrientation:updateStatusBar:duration:force:] + 331

frame #24: 0x0000000110b2b43e UIKit`__57-[UIWindow _updateToInterfaceOrientation:duration:force:]_block_invoke + 98

frame #25: 0x0000000110b2b38e UIKit`-[UIWindow _updateToInterfaceOrientation:duration:force:] + 391

frame #26: 0x0000000110b2b7d0 UIKit`-[UIWindow _updateInterfaceOrientationFromDeviceOrientation:] + 316

frame #27: 0x00000001106b054c CoreFoundation`__CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12

frame #28: 0x00000001105aea04 CoreFoundation`_CFXNotificationPost + 2484

frame #29: 0x000000010fed0968 Foundation`-[NSNotificationCenter postNotificationName:object:userInfo:] + 66

frame #30: 0x0000000110d52e59 UIKit`-[UIDevice setOrientation:animated:] + 282

frame #31: 0x0000000110aee047 UIKit`-[UIApplication handleEvent:withNewEvent:] + 1507

frame #32: 0x0000000110aee4da UIKit`-[UIApplication sendEvent:] + 79

frame #33: 0x0000000110ad9b8f UIKit`_UIApplicationHandleEvent + 593

frame #34: 0x0000000113c1b38c GraphicsServices`_PurpleEventCallback + 756

frame #35: 0x0000000113c1ae74 GraphicsServices`PurpleEventCallback + 35

frame #36: 0x00000001106146a9 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 41

frame #37: 0x000000011061461b CoreFoundation`__CFRunLoopDoSource1 + 475

frame #38: 0x0000000110609e68 CoreFoundation`__CFRunLoopRun + 2200

frame #39: 0x0000000110609366 CoreFoundation`CFRunLoopRunSpecific + 470

frame #40: 0x0000000113c19a3e GraphicsServices`GSEventRunModal + 161

frame #41: 0x0000000110ad9900 UIKit`UIApplicationMain + 1282

frame #42: 0x000000010fe48d6f TestKWS`main(argc=1, argv=0x00007fff4fdb7548) + 111 at main.m:14

2015-06-19 11:50:10.643 TestKWS[12305:761940] Keyboard will show

(lldb) bt

* thread #1: tid = 0xba054, 0x000000010fe48980 TestKWS`-[ViewController keyboardWillShow:](self=0x00007fa84381e1d0, _cmd=0x000000010fe48e92, notification=0x00007fa84166aaf0) + 64 at ViewController.m:51, queue = 'com.apple.main-thread', stop reason = step over

* frame #0: 0x000000010fe48980 TestKWS`-[ViewController keyboardWillShow:](self=0x00007fa84381e1d0, _cmd=0x000000010fe48e92, notification=0x00007fa84166aaf0) + 64 at ViewController.m:51