What is better place for loading data from API- viewDidLoad, viewWillAppear or viewDidAppear?

Question

I am making an IOS app where i am calling an API in viewDidLoad method of view controller. Now i want to reload the same view controller with the data that comes from server

Answer 1

viewDidLoad is called once. If you use navigation controller and do back and forth ou view controller this viewDidLoad method will never be called. Until you create this ViewController again (i.e [navContoller pushViewController]). If your api data will never changed the life cycle of this View Controller the this is the better place to call your API. But if your api data need to call frequently [i.e. back and push.forth this view controller] then you should not call api here.

viewWillAppear: before a view controller shows.If you call you api inside this method you UI will stack until the data loading finish. which looks odd.before load the view of viewController this "viewWillAppear" method is called. This is the reason, it's name is "viewWillAppear". That means this view will load some time later (i.e some micro second later). If you call your api here after what will happen lets analyze. Say, your api return response after 10 sec. Then UI will freeze/stuck for 10 sec and you will see after this 10 sec later your view will called.

viewDidAppear: after finished a view controller showing.So, you need to called your loading API inside this method.