Multiple NSNotifications when screen rotates - ios

Question

I’m getting multiple UIKeyboardDidShowNotification and UIKeyboardDidHideNotification notifications when I rotate the device and I can’t figure out why.
I have an app that lets you edit the text for each picture. (It’s in a UITextView.) Most of the time I need to slide the text up so you can see it above the keyboard, then I slide it down when you are done editing. Then I do a database update to save the new text. I use notifications to tell me when the keyboard is displayed and when it goes away. It works fine on iPad when the user taps the keyboard close icon on the keyboard. It also works fine if the user swipes to the next page and iOS closes the keyboard. Since iPhones and iPods don’t have a keyboard close key, I wrote a method to close the keyboard when the picture or background is tapped. It works fine there too. However, when I rotate the device, I get multiple hide and show notifications. And I don’t know why.
Instead of getting one UIKeyboardDidHideNotification notification, I get a hide, a show, a hide, and then a show.
2:39:44.200 Picts for SLPs[16533:907] keyboardDidHide called. Keyboard showing flag is YES.
2:39:51.751 Picts for SLPs[16533:907] keyboardDidShow called. Keyboard showing flag is NO.
2:39:55.224 Picts for SLPs[16533:907] keyboardDidHide called. Keyboard showing flag is YES.
2:39:56.124 Picts for SLPs[16533:907] keyboardDidShow called. Keyboard showing flag is NO.
I posted the relevant code below. It is taken mostly from StackOverflow posts (Thanks guys).
In my class that displays the pictures I start notifications when it is initialized.
- (id)initWithParentView:(UIView *)parentview {
self = [super init];
if (self) {
_parentView = parentview;
if (ALLOW_DATABASE_EDITING) [self startNotifications];
}
return self;
}
- (void)startNotifications {
// Listen for keyboard appearances and disappearances
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardDidShow:)
name:UIKeyboardDidShowNotification
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardDidHide:)
name:UIKeyboardDidHideNotification
object:nil];
}
The View Controller calls the hideKeyboard method in the View when the user taps on the picture.
- (void)dismissKeyboard {
if (self.showArtic.keyBoardIsShowing) {
[self.showArtic hideTheKeyboard];
}
}
resignFirstResponder sends a notification that closes the keyboard
- (void)hideTheKeyboard {
id <ShowArticDelegate> SA_delegate = _delegate;
// Don't update the database when there is no text.
if ( ![self.editableTextView.text isEqualToString:#""] ) {
[SA_delegate updateTextInDatabase:self.editableTextView.text];
}
[self.editableTextView resignFirstResponder];
}
These methods respond to the notifications.
- (void)keyboardDidHide:(NSNotification *)notification {
NSLog(#"keyboardDidHide called. Keyboard showing flag is %#.", self.keyBoardIsShowing ? #"YES" : #"NO");
self.keyBoardIsShowing = NO;
// Move the text, update the database
}
- (void)keyboardDidShow:(NSNotification *)notification {
NSLog(#"keyboardDidShow called. Keyboard showing flag is %#.", self.keyBoardIsShowing ? #"YES" : #"NO");
self.keyBoardIsShowing = YES;
// Move the text
}

Answer 1

any chance you could manually dismiss the keyboard and clean up your database from within this method:
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
and then if you want the keyboard brought back up once the rotation completes, manually call your method to display it from within:
- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation {
That may or may not fit your needs, but it's a pretty common and clean technique to "get out of the way" while Apple handles the rotation, and then get back to business once everything is back on solid ground again.