UIKeyboard adopts an invalid frame - ios

Question

I currently have an UICollectionView, and a UITextField on the bottom of the screen. The textField moves according to the frame of the keyboard (very much like an inputAccessoryView, but I didn't use it for other reasons), and the collection view gets its insets modified when the keyboard appears, very standard stuff.
Anyway, there's a button in the screen, that on press, shows a modal UIViewController that covers the entire screen, and I dismiss the keyboard if my textField isFirstResponder.
Now, when this modal view finishes its business, it gets dismissed, we are back at the collection view and textfield, but now, the collection view has infinite insets, and the keyboard doesn't show again.
I check the notification I get for UIKeyboardWillChangeFrameNotification, and this is the userInfo:
Printing description of notification:
NSConcreteNotification 0x1ee4e900 {name = UIKeyboardWillChangeFrameNotification; userInfo =
{
UIKeyboardAnimationCurveUserInfoKey = 0;
UIKeyboardAnimationDurationUserInfoKey = "0.4";
UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {320, 0}}";
UIKeyboardCenterBeginUserInfoKey = "NSPoint: {160, 1136}";
UIKeyboardCenterEndUserInfoKey = "NSPoint: {160, 568}";
UIKeyboardFrameBeginUserInfoKey = "NSRect: {{inf, inf}, {0, 0}}";
UIKeyboardFrameChangedByUserInteraction = 0;
UIKeyboardFrameEndUserInfoKey = "NSRect: {{inf, inf}, {0, 0}}";
}}
The keyboard is coming up as {{inf, inf}, {0, 0}}. I already wrote a check (with isInf) to prevent this, but now the keyboard gets permanently screwed up, and it won't show up anywhere in the app anymore, so this has become a serious issue. This happens on iOS6 and iOS7, on simulator and device.
I'm going through all the code to see if there's anything weird that is causing the issue, but I'm hoping some has ran into something similar, and has some insight on what is causing this.

Answer 1

After 3 months, I finally figured it out (I've been doing other stuff, FYI).
The short answer
Make sure you're not returning crap from any rotation method, otherwise keyboard goes loco.
The long version
Discovered by using the application Reveal, that draws a 3d decomposition of each layer in the app. I noticed the keyboard was being presented but it's frame was landscape, when the interface was in portrait. This immediately made me revise the whole way the rotation is being handled.
The whole problem spans from a UIViewController that posses child view controllers with a complex structure, and the rotation calls are getting forwarded to the children manually. For example, this method:
- (NSUInteger)supportedInterfaceOrientations
{
return [[[(id)self.selectedViewController viewControllers] lastObject] supportedInterfaceOrientations];
}
Was relying on whatever top-most view controller on the current selected navigation controller to return the value. Well, one of the view controllers went rogue, it wasn't returning anything here, so the return value must've been just about anything in memory or zero.
The solution now checks if the view controllers responds to the method, and if not, it defaults to portrait (which is about 90% of the app).
- (NSUInteger)supportedInterfaceOrientations
{
NSUInteger supported = UIInterfaceOrientationMaskPortrait;
UIViewController *viewController = [[(id)self.selectedViewController viewControllers] lastObject];
if (viewController && [viewController respondsToSelector:#selector(supportedInterfaceOrientations)])
supported = [viewController supportedInterfaceOrientations];
return supported;
}
Btw, the sane way to do it would be to just return YES from -(BOOL)shouldAutomaticallyForwardRotationMethods (iOS 6, 7) but this was an impossibility due to how it was implemented. For now, it's on NO and being manually handled.
There's still the question why it only mattered with presented view controllers. Although, I rather just discard it as "random behavior from returning an invalid interface orientation".