UITextField won't becomeFirstResponder - ios

Question

I'm having a problem getting a textfield to accept the becomeFirstResponder directive.
I'm providing a custom mechanism to create a title in the navigation bar. I have another viewcontroller that is successfully using this same technique. On viewDidAppear I fire off:
- (void)addTitleTextField
{
CGRect textFrame = self.parentViewController.navigationController.navigationBar.frame;
textFrame.size.width = 300.0;
textFrame.origin.y = (768.0 - 300.0)/2;
textFrame.size.height = 30.0;
textFrame.origin.x = 7.0;
self.titleTextField = [[UITextField alloc] initWithFrame:textFrame];
self.titleTextField.placeholder = NSLocalizedString(#"New Multiple Choice Quiz", #"New Multiple Choice Quiz");
self.titleTextField.borderStyle = UITextBorderStyleRoundedRect;
self.titleTextField.font = [UIFont boldSystemFontOfSize:20.0];
self.titleTextField.textAlignment = NSTextAlignmentCenter;
self.titleTextField.backgroundColor = [UIColor whiteColor];
self.titleTextField.textColor = [UIColor blackColor];
self.titleTextField.delegate = self;
[self.titleTextField setAutocorrectionType:UITextAutocorrectionTypeNo];
self.titleTextField.clearButtonMode = UITextFieldViewModeWhileEditing;
[self.titleTextField setAutocapitalizationType:UITextAutocapitalizationTypeNone];
self.activeTextField = self.titleTextField;
self.parentViewController.navigationItem.titleView = self.titleTextField;
[self.titleTextField becomeFirstResponder];
}
self.titleTextField will allow me to set the text value, but if you check using canBecomeFirstResponder it returns NO. As you can see I am setting this on the parentViewController. I've tried using a delegate to attempt to get the parentViewController to set it. When I do the delegate and check whether the textField canBecomeFirstResponder it returns YES, but I'm still unable to make it accept the firstResponder order. Any ideas? The Docs say "A responder object only becomes the first responder if the current responder can resign first-responder status (canResignFirstResponder) and the new responder can become first responder".

Answer 1

Are you telling the UITextField to become selector on a background thread?
[textField performSelectorOnMainThread:#selector(becomeFirstResponder) withObject:nil
waitUntilDone:YES];
Rationale: Calling UIKit methods (ie updating the view) on a method other than the main thread won't work. . this could be happening. (It is not clear where the addTitleTextField method is being called from).
Is there another first responder that needs some time to resign?
[textField performSelectorOnMainThread:#selector(becomeFirstResponder) withObject:nil afterDelay:0.0];
Rationale: If another field is hanging onto first responder (or in the process of resigning it), it will give it time to clean up an resign, by waiting until the next run-loop. . . . . usually the next run-loop will be enough time for the previous responder to clean up, or you could try a short delay like 0.05.

Answer 2

You might need to add textField to view hierarchy:
v.addSubview(textField)

Answer 3

Another thing to do is to make sure the textField is enabled (check Interface Builder, then any disabling you might do through code).
I spent almost an hour trying to figure out what the problem was: I got a workaround by subclassing UITextField and overriding canBecomeFirstResponder to always return true. This forced it to finally show keyboard and edit the textField, but I noticed I couldn't tap/select/copy/paste the textField. User Interaction was enabled, and then I finally saw the Enabled not being checked...I blame Apple for not displaying any visual cue when a piece of UI is disabled (like the do with Hidden) lol