Automatic view pushing when keyboard covers a text field depending on the position of the textfield in the window.

MyViewController.h

#import <UIKit/UIKit.h>

@interface MyViewController : UIViewController
@end

MyViewController.m

#import "MyViewController.h"

@interface MyViewController () <UITextFieldDelegate>

@property(nonatomic, weak) IBOutlet UITextField *txtDescription; 
@property(nonatomic, assign) CGFloat viewMoveUpOffsetForKeyboard; //for keeping track of the keyboard's view push height

@end

@implementation MyViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    self.txtDescription.delegate = self;
}


#pragma mark - UITextFieldDelegate

#define AVERAGE_KEYBOARD_HEIGHT 260 //Average iOS keyboard height in pixels, for both iPhone SE/5S/5 and 6/6s/7/7s/6S+/7S+

-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
        self.viewMoveUpOffsetForKeyboard = 0;
    }
    [textField resignFirstResponder];
    return NO;
}

-(void)textFieldDidBeginEditing:(UITextField *)textField
{
    float screenHeight = [UIScreen mainScreen].bounds.size.height; //height of the device screen
    CGPoint textFieldXYPointInWindow = [textField convertPoint:CGPointMake(0, 0) toView:nil]; //current textfield's (x,y) point in window
    float textFieldBottomPoint = textFieldXYPointInWindow.y + textField.frame.size.height; //bottom point of the text field
    
    if  (screenHeight - textFieldBottomPoint < AVERAGE_KEYBOARD_HEIGHT) //is the textfield under keyboard?
    {
        self.viewMoveUpOffsetForKeyboard = AVERAGE_KEYBOARD_HEIGHT - (screenHeight - textFiledBottomPoint) + 30; //this 30 is just an offset
        if(self.view.frame.origin.y >= 0)
            [self setViewMovedUp:YES];
    }
}

-(void)textFieldDidEndEditing:(UITextField *)textField
{
    if (self.view.frame.origin.y < 0) //already view moved up? Bring it down
    {
        [self setViewMovedUp:NO];
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view
    
    CGRect rect = self.view.frame;
    if (movedUp)
    {   // 1. move the view's origin up so that the text field that will be hidden come above the keyboard
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= self.viewMoveUpOffsetForKeyboard;
        rect.size.height += self.viewMoveUpOffsetForKeyboard;
    }
    else
    {   // revert back to the normal state.
        rect.origin.y += self.viewMoveUpOffsetForKeyboard;
        rect.size.height -= self.viewMoveUpOffsetForKeyboard;
    }
    self.view.frame = rect;
    
    [UIView commitAnimations];
}
#pragma mark - end of UITextFieldDelegate

@end