keyboardWillShowNotification

keyboardWillShowNotification.m

- (void)keyboardWillShowNotification:(NSNotification *)notification {
    
    dispatch_async(dispatch_get_main_queue(), ^{
        UIView *workingView = self.view;
        CGRect keyboardScreenRect = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
        CGRect keyboardRect = [workingView convertRect:keyboardScreenRect fromView:nil];
        CGRect resizeRect = [workingView convertRect:_resizingView.superview.bounds fromView:_resizingView.superview];
        CGRect unionRect = CGRectIntersection(keyboardRect, resizeRect);
        CGFloat bottom = resizeRect.origin.y + resizeRect.size.height;
        if (!isinf(unionRect.origin.y)) {
            bottom = unionRect.origin.y;
        }
        
        CGRect newFrame = _resizingView.frame;
        newFrame.size.height = [_resizingView.superview convertPoint:(CGPoint){.x=0.0f, .y=bottom} fromView:workingView].y - newFrame.origin.y - 5.0f;
        _resizingView.frame = newFrame;
    });
    
}