title: becomeFirstResponder not working in iOS 8
body: <p>I am using UITextField's method becomeFirstResponder to show the keyboard.
  This is working in iOS 7. But in iOS 8 this method doesn't show the keyboard.</p>
  
  <pre><code> UITextField *txtAddNew = [[UITextField alloc] initWithFrame:CGRectMake(10,10,240, 21)];
   txtAddNew.font = [UIFont fontWithName:@"Helvetica" size:16];
   txtAddNew.clearButtonMode = UITextFieldViewModeWhileEditing;
   txtAddNew.returnKeyType = UIReturnKeyDone;
   txtAddNew.delegate = self;
   txtAddNew.autocorrectionType = UITextAutocorrectionTypeNo;
   txtAddNew.tag = 15;
  
   // Open keyboard
   [txtAddNew becomeFirstResponder];
  </code></pre>
  
  <p>Is there any way to do it in iOS 8?</p>