iPad上的UIModalPresentationFormSheet。 键盘出现时如何调整UITextView高度

Question

UITextView is subview of the modal controller view. I need to decrease UITextView height when keyboard appears in order to bottom border y coordinate of the UITextView to be equal to keyboard's top y coordinate. I'getting keyboard height

CGRect frameBegin = [[notification.userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue] ;
CGRect frameEnd = [[notification.userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];

CGRect resultBegin = [self.view convertRect:frameBegin fromView:nil];
CGRect resultEnd = [self.view convertRect:frameEnd fromView:nil];

CGFloat kbdHeight = resultBegin.origin.y  - resultEnd.origin.y;

The problem is that this modal view jumps up when keyboard appears. How to calculate keyboard's top border coordinate in this case?

Answer 1

You could do this:

1. Register for keyboard notifications:

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(myTextViewHeightAdjustMethod:)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(myTextViewHeightAdjustMethod:)
                                             name:UIKeyboardDidShowNotification
                                           object:nil];

2. Calculate intersection and adjust textView height with the bottom constraint

    - (void)myTextViewHeightAdjustMethod:(NSNotification *)notification
    {
        NSDictionary *userInfo = [notification userInfo];
        CGRect keyboardFinalFrame = [[userInfo emf_ObjectOrNilForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];

        CGPoint keyboardOriginInView = [self.view convertPoint:keyboardFinalFrame.origin fromView:nil];

             CGFloat intersectionY = CGRectGetMaxY(self.view.frame) - keyboardOriginInView.y;

             if (intersectionY >= 0)
             {
                 self.textViewBottomConstraint.constant = intersectionY + originalTextViewBottomConstraint;

                 [self.textView setNeedsLayout];
    }

Remember to unregister for notifications.

Answer 2

If you don't need to write the code for this yourself I recommend using https://github.com/hackiftekhar/IQKeyboardManager

It works great (for me, so far) and all you need to do is import it and add this one line of code in AppDelegate:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    //Magic one-liner
    IQKeyboardManager.sharedManager().enable = true

    return true
}