becomeFirstResponder very slow

Question

I have the following viewDidLoad method:

- (void)viewDidLoad {
    NSLog(@"didLoad");
    if (self.loginField.text.length > 0) [self.passwordField becomeFirstResponder];
    else [self.loginField becomeFirstResponder];
}

I also add log times in viewWillAppear and viewDidAppear .

There are some situations when push animation takes much time. I have measured the time with commented (and without) if-else lines (see: the times are shown below). I don't know what can slow down my app between viewWillAppear and viewDidAppear calls.

I tried to anayze this fragment of code with Time Profiler (Instruments), but it shows nothing. I have no clue what should I do, to show my view faster. Any ideas?

With becomeFirstResponder, first call

2014-07-11 16:51:41.090 didLoad
2014-07-11 16:51:41.133 willAppear
2014-07-11 16:51:44.223 did appear
diffAppear = 3090ms

With becomeFirstResponder, second call

2014-07-11 16:52:01.370 didLoad
2014-07-11 16:52:01.400 willAppear
2014-07-11 16:52:02.109 did appear
diffAppear = 709ms

Without becomeFirstResponder, first call

2014-07-11 16:57:21.720 didLoad
2014-07-11 16:57:21.754 willAppear
2014-07-11 16:57:22.420 did appear
diffAppear = 666ms

Without becomeFirstResponder, second call

2014-07-11 16:57:31.851 didLoad
2014-07-11 16:57:31.870 willAppear
2014-07-11 16:57:32.541 did appear
diffAppear = 671ms

Answer 1

As @holex metion in comments:

the –becomeFirstResponser normally loads the input views for the actual object which takes time. on the other hand, you should call this method after your view is in the navigation stack and in the view-hierarchy properly, which means in that case: in or after the –viewDidAppear: method, not sooner.

I moved –becomeFirstResponser to -viewDidAppear: . Now according to this question I added these observers as shown below and now app as it should.

- (void)willShowKeyboard:(NSNotification *)notification {
    [UIView setAnimationsEnabled:NO];
}

- (void)didShowKeyboard:(NSNotification *)notification {
    [UIView setAnimationsEnabled:YES];
}

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willShowKeyboard:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didShowKeyboard:) name:UIKeyboardDidShowNotification object:nil];

It is not a perfect solution (push animation haven't got keyboard) but is good enough for me.