Dismiss Numpad/keyboard when touching outside UITextField

There are two kinds of method to achieve it.

Method 1:

To add an UITapGestureRecogniser and assign it to the view, and then call the function to resign the keyboard.

in viewDidLoad:

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] 
                                       initWithTarget:self
                                       action:@selector(dismissKeyboard)];

[self.view addGestureRecognizer:tap];

-(void)dismissKeyboard {
       [aTextField resignFirstResponder];
}

Method 2:

to make your UIView as an instance of UIControl and then link its "Touch Up Inside" event to (IBAction)dismissKeyboard:(id)sender method. 

- (IBAction)dismissKeyboard:(id)sender {
    [aTextField resignFirstResponder];
}