问题
(I'm targetting iOS 2.0 for the time being.)
I have a class which subclasses UITextField and implements the UITextFieldDelegate protocol.
At first, I did not set the class as its own delegate, and when I clicked in the field, the keyboard popped up automatically. So far, so good.
I send the setReturnKeyType: message with UIReturnKeyDone, so it changes the bottom-right button to say Done.
The problem was, when I clicked Done or pressed [Return], nothing happened - the keyboard wouldn't go away.
I tried adding self as an observer for the end editing notification, but it never got called when Done was clicked; from a Google search it seems that only gets fired when the field resigns as the first responder - which is the bit I can't get to happen.
I then found answers on here that suggested adding self as the delegate and handling textFieldShouldReturn:. The problem is, as soon as I add self as the delegate, the keyboard no longer pops up when you click the field (and it doesn't gain focus) - it seems it isn't becoming first responder.
I tried handling textFieldShouldBeginEditing: and returning YES (docs say that should be the default if not overridden), and that got called, but made no difference. In my ignorance I tried [textField becomeFirstResponder] and was rewarded with a stack overflow (now I know that is called in response to trying to become first responder).
I'm now thoroughly stuck!
Can anyone help? I just want the keyboard to go away when the user clicks Done or presses [Return].
回答1:
Are you using an xib or doing it programatically? If you are using an xib then you may have forgotten to connect the delegate in File's Owner.
(BOOL)textFieldShouldReturn:(UITextField *)textField
{
[textField resignFirstResponder];
return YES;
}
Try This one.
回答2:
My fault. Turns out you're not supposed to set a text field's delegate to itself - there are complications due to unhandled selectors being forwarded to its delegate. If it doesn't respond to a selector the message goes to its delegate... which is itself, which we already know doesn't respond. Hence, an infinite loop.
Using a separate object as the delegate worked perfectly.
Hopefully this will help someone else avoid the same problem.
来源：https://stackoverflow.com/questions/11030142/problems-with-uitextfield-keyboard-management-in-ios