textFieldShouldReturn：没有被调用但textFieldDidEndEditing：被调用？

Question

我在UIAlertController中有一个文本字段，我正在尝试实现委托方法textFieldShouldReturn：它不会被调用。但我尝试实现方法textFieldDidEndEditing：调用没有任何问题。请帮帮我。我就是这样做的，

 __weak typeof(self) weakSelf = self;

    [alertController addTextFieldWithConfigurationHandler:^(UITextField
    *textField) {
            textField.placeholder = @"Product upc";
            textField.textAlignment = NSTextAlignmentCenter;
            textField.returnKeyType = UIReturnKeyGo;
            textField.delegate = weakSelf;

        }];

- (BOOL)textFieldShouldReturn:(UITextField *)textField{

    NSLog(@"textfield should return");
    //do something
    [textField resignFirstResponder];
    return NO;

}

- (void)textFieldDidEndEditing:(UITextField *)textField {

    NSLog(@"end editing ");
}