Logic For Moving Text Field Above Keyboard On Tap

Question

Right now, I have basic code for moving the textfield above the keyboard when you start editing. However, the size of the textfield varies based on device and orientation. S

Answer 1

Using notification keyboard register , you can place your textfield inside a scroll and manage the content offset of scroll to turn the actual first responder above keyboard if it's neccesary.

so after register controller to keybard appear , you must to obtain the gap between keyboard origin and scroll origin relative to parent.

you must know if an specific first responder can change content offset of scroll, therefore is neccesary to know the possible bounds between keyboard origin and first responder.

by the way you need to know the gap betwen the scroll content offset and the first responder for place your first responder in specific position.

@interface MainViewController : UIViewController

  @property (strong, nonatomic) IBOutlet UIScrollView *scroll;

@end    

@interface MainViewController ()
{
   CGPoint scrollOffset;
}
@end 

@implementation MainViewController

@synthesize scroll

-(void)viewWillAppear:(BOOL)animated
 {
    [[ NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillAppear:) name:UIKeyboardDidShowNotification object:nil];

    [[ NSNotificationCenter defaultCenter ] addObserver:self selector:@selector(keyboardWillDisAppear:) name:UIKeyboardDidHideNotification object:nil];

 }


-(void)viewWillDisappear:(BOOL)animated
 {
    [[ NSNotificationCenter defaultCenter ] removeObserver:self ];
 }

-(void)keyboardWillAppear:(NSNotification*) note
 {
   const CGFloat default_gap = 25.0f;

   NSValue *keyBoardEndFrameValue = [[ note userInfo ] objectForKey:UIKeyboardFrameEndUserInfoKey ];

   CGRect keyBoardFrame = [ keyBoardEndFrameValue CGRectValue ];


   offset = scroll.contentOffset;

   UIWindow *window = [[ UIApplication sharedApplication ] keyWindow];
   UITextField *textField = (UITextField*)[ window performSelector:@selector(firstResponder) ];

   //Gap between keyboard origin and the scroll origin, relative to parent.
   CGFloat distanceRelativeToParent = keyBoardFrame.origin.y - scroll.frame.origin.y; 


   //Distance between superview to textfield inside scroll. to determine if it's necesary to scroll.
   CGFloat bound = (textField.frame.origin.y + textField.frame.size.height)+scroll.frame.origin.y; 

   CGFloat gapScroll = textField.frame.size.height+default_gap;

  if( bound >= keyBoardFrame.origin.y )
   {
     [ UIView animateWithDuration:.3 delay:0.0 options:UIViewAnimationCurveEaseOut 
   animations:^{

        [ scroll setContentOffset:CGPointMake(0, textField.frame.origin.y - distanceRelativeToParent +  gapScroll  ) animated:YES ];

   }
  completion:^(BOOL finished){

   }];
}

}

-(void) keyboardWillDisAppear:(NSNotification*) note
{   
   [ scroll setContentOffset:offset animated:YES ];
}
@end