I have first view controller and second view controller. I will go from first view controller to second view controller. After that, I will go to other application or browse for some time. Then, when I come back, it always go back to first view controller as the new application open. How shall I just stay in particular view after I come back ?
Read about State Preservation and Restoration , it's very useful in your case
Do you mean your app again start with the first view controller, after coming into active state?
I think app start from where it left.
Either you're doing something in the code to load the first view controller again, or
you can store the state and on coming into foreground can reset the previous state.
Related
My app consists of two views. The first one is a GMSMapView and the second one is used to connect to a Bluetooth device that sends coordinates.
After the Bluetooth device is connected, I use a delegate to send the information back to the map view and move a marker around. To transition between views I was previously using segues, this didn't stop the Bluetooth view controller and the data made its way like I wished to the map view.
I ran into the problem of my map view being reinitiated so I decided to use a navigation controller. Now I use a push segue to get to my second view, and pop to come back to the same instance of the first one. Great, that worked! The issue I have now is that popping the second view seems to stop it completely from running in the background like it used to. Is there a way to keep it running in the background like it did before?
What I'm currently using to pop the second view is
self.navigationController?.popViewControllerAnimated(true)
Any idea would be appreciated! Thanks!
A popped view controller does not "stop running". It is returned to you, and if you don't retain it, it is completely destroyed.
If you don't want that to happen, retain it when it is returned. You are currently ignoring the returned view controller:
self.navigationController?.popViewControllerAnimated(true)
Instead, keep a reference to it:
self.mySecondViewController =
self.navigationController?.popViewControllerAnimated(true)
Be warned, however, that this is a very unusual architecture. You will not be able to use the storyboard segue to push again, because it will push a different copy. It would be better to abandon your navigation controller architecture entirely, as it is completely unsuited to the idea of a view controller persisting after it is popped. If you want an architecture where two view controllers persist simultaneously, you would be better off using a UITabBarController — or, even better, reorganize your app completely. The notion that you need the view controller to persist after being popped is a "bad smell": it means that you have put the functionality in the wrong place. Put the functionality in a place that does persist, rather than forcing the view controller to persist in some artificial way.
I would like to create a "deep link" into my storyboard while preserving the backstack (back button navigation).
Ex:
Given the storyboard below (entry point being the leftmost Navigation controller)
When my application is opened via a remote notification I would like to open the second tab in by tab controller AND be able to navigate back to the item list via the back button.
Please note that I am not asking about how to open the second tab, or how to create such a storyboard but specifically if there is a way to do this with storyboards or will I have to do it by code.
Thanks!
PS: I come from an Android background where one recreates the parent view controller manually or (better) inserts it into the backstack. As far as my research goes there is no such thing in ios. I'm hoping I'm wrong.
Your UINavigationController has a viewControllers property. You can create as many view controllers as you want in an NSArray and assign it to this property and that will be the back stack with the last VC in the array displayed.
The problem is that when a notification arrives, your app could be in any state at all. It could be running, with some other screen showing. It could be suspended, with some other screen showing. Or it might not be running at all, and will now have to be launched from scratch.
Thus, starting in the App Delegate routine that responds here, you will have to deal manually (in code) with the situation if you want to put your app into an appropriate state.
iOS 7 introduces edge swiping to navigate backwards in a navigation controller (so long as you don't override the leftBarButtonItem, among other things).
Imagine I'm implementing an app similar to Apple Notes. In Apple's app, once the user taps into a note, there is a Back button on the top left, and a Done button on the top right. This view controller is automatically saved after the user navigates away. Even if the user swipes backwards while still editing the note, it will auto-save.
One way to implement this is to write to disk on each key stroke. However, I'm looking for a more efficient implementation.
Which method should I override to perform my auto-save?
To be clear, the auto-save code should be invoked in these three cases:
The user taps the Back button
The user swipes backwards
The user taps the Done button
So far, I've been implementing the save logic in viewWillDisappear, this minimizes the amounts of writes, and also takes care to save if the user kills the app.
Additionally, instead of implementing save logic in the Done button, the Done button can simply call:
[self.navigationController popViewControllerAnimated:YES];
... (e.g. via a delegate, or unwind segue) and it will automatically save as well. All three code paths will go through viewWillDisappear.
Although it could technically be implemented in viewDidDisappear, if the previous view controller needs to display the updated data, this method will be too late.
For more complex view controllers (e.g. those that have destructive behavior once the view controller is dismissed), there are several other things to consider:
Should the save be called if a modal is presented above the current view controller? (e.g. In Apple Notes, imagine that the share button launched a modal; should it save when you tap on this button?). If it is important not to save at this time, you can read the value of presentedViewController. If it has a value, that means viewWillDisappear is being called because a modal is being presented above it.
Should the save be called if a view controller is pushed on to the current navigation stack? (e.g. Again, in Apple Notes, if the share button used a push instead of a modal, should it save?) You can check the value of isMovingFromParentViewController in this case.
If the user taps the home button to quit your app, should it save?
If the user begins swiping backwards then cancels the swipe to stay on the current screen, should it save?
Imagine the view controller is in a modal, when the modal is dismissed should the destructive action happen? Check isBeingDismissed in this case.
Same as above, but imagine the view controller is the second page in a navigation controller than is being presented.
I've two view controller.
In the first, i write my room's name (for example bedroom) and push the button.
In second view, i see the name of my room, and insert other details, like number of bulbs, name of bulbs and when i've finished, I press on a button that keeps me coming back to previous controller.
I'm using uinavigation bar for this two steps, but i have a question.
If I press on bedroom's button, i don't see the details that i've wrote before.
How i can see that?
As you have discovered, when you go back from your second view controller to the first, the second is deallocated and its contents are lost. When you go forward again, a completely new instance of your second view controller is created.
To overcome this, you need to pass the current data from the first to the second, and then pass back any changes when the user goes back to first (before the second view controller is deallocated). There is a very good explanation of this, with various options for achieving it, in this question.
just you add on button click this method .
[self.navigationController popToRootViewControllerAnimated:YES];
I'm using the Facebook iOS SDK to have users authenticate and when they log out and log back in, the state of the main view controller, the one with the logout button, is in the same state as when they left it.
How can I completely remove the view controller from memory so that every time they log back in, the view controller's viewDidLoad method is called and the view controller is re-initialized.
When done with it each time you need to release all references.
When you need to show it again, create and use a new instance. This is the only way to ensure viewDidLoad is called each time you need it.
Or if you want to keep reusing the same one over and over, add a restart method (or something similar). The implementation of this method can reset the UI to whatever starting state you need. Or you can put this logic in the viewWillAppear: method. This depends on whether viewWillAppear: can be called due to pushing and popping other view controllers.