becomeFirstResponder works in viewDidAppear but doesn't work in viewDidLoad

Possibly it does not work in viewDidLoad, as view does not added into view hierarchy yet. But according to apple documentation becomeFirstResponder should be called only on objects attached to UIWindow:

However, you should only call it on that view if it is part of a view hierarchy. If the view’s window property holds a UIWindow object, it has been installed in a view hierarchy; if it returns nil, the view is detached from any hierarchy.

So, i assume, the best place to achieve necessary behavior is to place call into viewWillAppear method.

Update.

So, in viewWillAppear controller's view not yet attached to UIWindow... it only notify, that view will be added to view hierarchy

It may be some tricky, but you can make some small delay in viewWillAppear:

 - (void)viewWillAppear:(BOOL)animated {    [super viewWillAppear:animated];    double delayInSeconds = 0.05;    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));    dispatch_after(popTime, dispatch_get_main_queue(), ^{         make first responder here    }); }

But I believe there is should be a better solution

You should call in viewDidLayoutSubviews(), the code below set textField becomeFirstResponder only at the first time view layout subviews, and it should be.

var isFirstLayout: Bool = trueoverride func viewDidLayoutSubviews() {    super.viewDidLayoutSubviews()    if isFirstLayout {        defer { isFirstLayout = false }        textField.becomeFirstResponder()    }}

all the IBOutlet objects are loaded in viewDidLoad,if you are calling the method in viewDidLoad then that action not performed because before the objects are loaded we can't do anything that's whybetter to write that code in

-(void)viewWillAppear:(BOOL)animated{//write here} 

then it works fine.