I have an application which has a single window controller and 2 view controllers.I have created a segue from a button within the main View Controller to the second View Controller;to show a modal window.
Is it possible to access the controls located within the second view controller by creating an outlet within the .swift file of the first view controller. i.e.:access controls within the second view controller from the first view controller.
What are you trying to achieve?
generally speaking - No. Button, labels, or view loaded by a view controller are only in scope (loaded into memory) when the view controller's view is displayed.
Very rarely would you need to initialize the view controller and make a method call before the view is displayed, so the real question is why are you wanting to do this.
Keep in mind its is called "view controller" i.e it controls the current views objects.
I believe there is flaw in your design by wanting to do this.
Making the assumption that the first view controller is not destroy when loading the second (i.e the second is a popup):
To properly communicate between the two view controllers you need two parts.
When performing the segue you need set parameter being passed to the second view controller.
https://developer.apple.com/documentation/appkit/nssegueperforming
Inorder to communicate back to first view controller you need to implement a delegate. I.e the second view controller delegates work back to the first:
https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html - view the section on delegation.
Related
I have two UITableViewControllers in a navigation controller with static cells that I am using for my form. I have a show segue from a cell on the first view to the second view, but when I hit the back button on the second view, all of the data in the text fields and pickers in the second view is erased. Why is that and how can I fix it?
The second view controller is created every time you perform the segue from the first to the second view controller. Therefore the initial state of the second view controller is re-created every time new. See this answer to understand the process better (It's the answer to question 3):
iOS Segue - When are the viewControllers Instantiated
You have many options to resolve this. E.g:
store the data in the second view controller on disk (e.g. with NSUserDefaults) and re-create if every time the view controller is created
store an instance of the second view controller in the first view controller and do not segue to it but call self.navigationController?.pushViewController to open the second view controller
etc...
I have one SplitView controller which i have set in Application Delegate class.
Now I want to do that I want to hide Split view only in one particular view controller other wise it will be shown.
I know the method to hide split view but it will be hidden or shown in all the view controller how can i do that for particular one view Controller.
-Thanx in advance
iOS 5 introduces the concept of custom container view controller and provides API like addChildViewController. Question: can you add a view controller as a child and still present it using presentViewController? Does doing the latter automatically make it a child view controller of the presentingViewController?
That's not how it's supposed to be used.
The parent/child relationship is for when a view controller has subviews that are managed by their own view controllers, for example a UITabBarController, where the parent view controller draws the tabs and the child view controllers draw the content of each tab.
If you present a view controller using presentViewController, it generally takes over the whole screen, or appears in a modal so that the presenting view controller is no longer in control. In that scenario there's no reason for the presenter to be the parent because it doesn't need to cooperate with the presented controller - it just gets out of the way until the presented controller is dismissed again.
Why is it that you wanted to do this? If it's just so that the view controllers have a reference to one another and can pass data, there are other ways to do this (e.g. the delegate pattern, NSNotifications, or even just a property linking the two).
When Switching between two view controllers, what's the difference between addSubView or using a navigation controller and using pushViewController?
In my app, I have a few set up screens in the beginning before a game calculator starts (which has a lot of view switching in between, and a lot of ViewControllers are reused).
In that case, should I set up a navigation controller in the AppDelegate or in the RootViewController, or just use addSubView in the first few set up screens and add a navigation controller where my calculator views start after the set up screens?
The difference is that with addSubiview, you add a view to another, which therefore will contain it. The navigation controller actually manages a stack of VC, in which the next view isn't included in the previous.
Another diference is about parameters, addSubview will accept a view as argument, while the other will accept a view controller.
Typically, a navigation controller is used when displaying hierarchical content (in a table view most of the time), that allow the user to go deeper in details, or getting back to previous levels.
Is it possible to have a single iPhone screen with its view loaded from a xib by that screen's UIViewController, but then another UIView within that screen with content loaded from a separate xib file? If so, is it possible to have that nested view's events handled by a separate custom UIViewController subclass from the rest of the screen? If both of these things are possible, are they also advisable?
It is possible. Apple suggests against having more than one UIViewController active on screen at once, so they would advise against. I would suggest only doing it if the reason for the second view controller is navigation or modal.
A view controller with the purpose of loading other view controllers, like a navigation controller, needs some screen space for itself and uses the rest to load another view controller. That is fine. The criteria here is that only one controller is presenting content while the other is presenting navigation.
A view controller could load another view controller to perform some limited task like selecting an item from a list or entering some text. The second view controller might only fill part of the screen. The criteria here is that the one controller behaves modally and will only be displayed long enough to get some user input.
As for the general case of splitting the screen between two view controllers that are presenting content, the Apple suggestion is that you have a single class derived from UIViewController manage the views. If the view is complex enough to warrant other controllers, then derive them from NSObject and have the master view controller manage the child controllers along with the views. The child controllers would have the master controller as a delegate, and the master controller would pass views to the child controllers to manage but not own.