A lot of times, we can only see the header files but not the source code. If I understood well your question, you would like to know about the application lifecycle, is it true? If you want to know how happens when an application starts, I suggest to read about app-launch-sequence-ios-revisited by Oleb.
It's a very good post. About the methods you wrote, these methods shouldn't not called manually. It's the framework through the iOS that calls them for you. You use override loadView when you cannot create a storyboard or a nib file. In this manner you can provide to your UIViewController a fresh view. From Apple doc:. How this is meant to work is that UIKit's code will call your loadView method if and when it actually needs to present that controller's view hierarchy on screen.
Specifically, if any code attempts to read your view property on your view controller, and that property is nil, then UIViewController's code will call the loadView method. If you don't implement loadView yourself, then the default implementation will fall back to attempting to load the view hierarchy from the nib. This all happens automatically when you attempt to present your view controller and the view is nil.
This can happen multiple times while your app is running if your view controller has to unload its view in response to memory pressure, another behavior you get for 'free' and that you don't want to call yourself. If these methods are not being called in your view controller, then there must be something wrong with how you are presenting this view controller, which is preventing the framework code in UIViewController from calling these methods.
Post that code and someone can help you figure out that bug. Before you attempt to fix that bug, though, you should remove these from your code:. And then in your own implementation of viewDidLoad , you will want to call the superclass' implementation with [super viewDidLoad]. Remember that in loadView your only responsibility to set self. That's it. UIKit code will then see that and call viewDidLoad for you. However, you may want to modify a specific part of the view every time the user gets to view it, e.
However, when you are loading things from a server, you also have to think about latency. If you pack all of your network communication into viewDidLoad or viewWillAppear, they will be executed before the user gets to see the view - possibly resulting a short freeze of your app. It may be good idea to first show the user an unpopulated view with an activity indicator of some sort. When you are done with your networking, which may take a second or two or may even fail - who knows?
Good examples on how this could be done can be seen in various twitter clients. For example, when you view the author detail page in Twitterrific, the view only says "Loading From Android R, this method always returns false. Google says that this is done "to protect goat privacy":. From their source , the method used to return false until it was changed in API It looks like the method has no real use for us as developers. Someone has previously stated that it might be an Easter egg.
In this way you can take actions to free some memory. Keep in mind that if you ignore memory warnings and the memory used by your app goes over a certain threshold, iOS will end your app. This will look like a crash to the user and should be avoided. Jump to Section. Edit Page Page History. When this is the case,init coder: is the initializer that gets called and you have to override. This is not used often, so you can ignore the parameter.
If you are curious, serialization transforms an object in a byte stream that you can save on disk or send over the network. Application : During the initalization phase of a view controller, you usually allocate the resources that the view controller will need during its lifetime. These include model objects or other auxiliary controllers, like network controllers. Previous view controllers might also pass these objects to the current one, so you do not always need to instantiate them in every view controller.
Things to take care of : Beware that the view of the view controller has still not been instantiated at this point. If you try to access it through the view property of UIViewController, the loadView method will be called. This might happen, for example, to work in a larger team where different members need to be change view controller interfaces without affecting the work of others.
You also might have a project that was created when storyboards did not exist yet, so every view controller had its own nib file. Keep in mind that if your main storyboard starts getting too big, you can split it into more storyboards.
0コメント