Create a new single-view project (e.g., 'Test')
Within the main storyboard, create two view controllers with titles One and Two - make One the initial view controller
Place the label One within the content of view controller One and label Two within Two
Include the following within the viewDidLoad of TestViewController.m:
// instantiate the new view controller
UIStoryboard *storyboard = self.storyboard;
TestViewController *viewController = [storyboard instantiateViewControllerWithIdentifier:#"Two"];
// Change the view
viewController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentViewController:viewController animated:YES completion:nil];
Save, build, and run.
I consistently get an error of the Storyboard does not contain view controller 'Two' variety. Using breakpoints, I've discovered that the problem is at the instantiation step. Yet the above code is taken directly from Apple's View Controller Programming Guide.
I've combed this site and discovered many people having problems with instantiating view controllers programatically. Any definite solution?
There's no bug here -- you're just writing inappropriate code. The code snippet you've given works fine if you put it in an action and trigger it with a button, a timer, etc. But you're attempting to present another view controller modally before the view controller running the code has even gotten around to displaying its own view.
-viewDidLoad is called when the view controller's view has been loaded from the storyboard or .xib file; it's an opportunity to do any initialization that had to be deferred until the view hierarchy comes into existence. However, the view isn't actually displayed at that point. You need to wait until you get a -viewDidAppear message to know that the view is on screen. So, you can imagine that it doesn't make a lot of sense to try to present some other view controller before the current one has even settled in.
I consistently get an error of the Storyboard does not contain view controller 'Two' variety.
In that case, you haven't properly assigned a storyboard identifier to the view controller. Select view controller "Two" in the storyboard editor and then look at the identity inspector. You need to set the identifier like this:
I've combed this site and discovered many people having problems with
instantiating view controllers programatically. Any definite solution?
Did you also look at the answers to their questions? That's how this site works -- we answer questions not just for the people that are asking them, but also to help others in the future who may have similar questions. Identifying a UIStoryboard is a good example of a question similar to yours with an answer that probably would have helped you.
Related
I am developing an application with iOS 9 based SDK , this is my first time I am working with Storyboards , I have 20 view controllers, each scene has Next / Previous buttons to go back and forward . I have a huge problem with going forward !. If I move from scene 1 to for example to scene 15 I received memory warning and then application crashes . I have searched and it seems there is method called unwind segue but it seems this is for going back ! it's something like dissMiss method .
I connect each scene with line in Interface Builder :
Here is segue's setting :
I would be grateful if you help me out .
EDITED :
I tried to present a view controller programmatically but result was the same ! .
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
WhatIsDino *vc = (WhatIsDino*)[mainStoryboard instantiateViewControllerWithIdentifier:#"WID"];
[self presentViewController:vc animated:YES completion:nil];
Seems like it's a problem of wrong approach, and not the storyboard.
Let me guess, since before storyboard you used to change your app's rootViewController to the next/previous screen once you tap on the arrow button. So previous screen are released and deallocated from memory once you set a new rootViewController.
And now you're presenting every next view controller modally, which involved creating new UIWindow and loads all the hierarchy of you screen and keeps previous underneath the new one so it holds the memory and you're getting out of memory crash.
Well, you can do rootViewController approach with a storyboard too since it's just another way to manage your screens while development. Storyboard offers additional features like segues, static table view cells, general tint color and so on. [UIStoryboard -instantiateViewControllerWithIdentifier:] is the method you might find interesting.
But I'd rather recommend you to check out the UIPageViewController, it's like a container for the screens. Unfortunately, it cannot have the segues to your scenes (because of the special way segues work) so you have to use -instantiateViewControllerWithIdentifier: method anyway. You can treat inner view controllers of UIPageViewController as you do with rootViewController before.
You can also navigate without segue and Its easy way I think.
If you want to navigate from Class1 to Class 2 then follow these steps.
1) In Class 1, Import Class2.
2) In your button Action, Write this code.
Class2 *next = [self.storyboard instantiateViewControllerWithIdentifier:#"Class2 Identifier name"];
[self.navigationController pushViewController:next animated:YES];
Do not forget to give Identifier name in story board that is "Storyboard ID" in Attribute inspector of particular class.
No need to add Segue,Your storyboard would look clean.
The problem is that you are adding view controller after view controller with modal presentation. That causes each view controller to be added on top of the previous one, and all of them accumulate, using more and more memory.
Using a navigation controller and a push also piles the view controllers on top of each other.
You will have this problem if you use storyboards, nibs, or create the view controllers manually.
If you have a design where the user can move through a large series of view controllers then you probably want to dismiss the previous one before pushing/presenting a new one.
You can probably dismiss the previous view controller without animation and then present the new view controller each time you want to display a new one and avoid the memory issue. i'd have to experiment with it to get the effect I was after, but that's what I would suggest.
I am interested in creating an app that starts with a menu which may possibly contain an options view, then steps from the menu view to a data-item selection view, then to a configuration view, and finally a result view that displays progress or changes. I want to have this process be repeatable like a loop, and have the user be able to jump backwards to a previous view if necessary. Jumping from view to view would of course be a user input / output with a button or something. FYI, I am using Xcode 5.1.1.
What would be the best approach to this? What kind of view controller is going to do the trick? I have heard a lot about navigation controllers, tables, etc.. but am having a hard time figuring out what to use in my case.
Below is a state-diagram similar to what I would like to do...
A UINavigationController should work great as your root view controller. It automatically includes a back button, and you can use the popToRootViewController method to return to the root of the navigation controller. You can set up a navigation controller as your root view controller from the applicationDidFinishLaunching method using this code.
MainMenuViewController *mainMenuViewController = [[MainMenuViewController alloc] init];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:mainMenuViewController;
self.window.rootViewController = navController;
For more information take a look at apples UINavigationController programming guide https://developer.apple.com/library/ios/documentation/uikit/reference/UINavigationController_Class/Reference/Reference.html
Each of your other screens may use different types of view controllers depending on their specific needs. If you need to display a list of items, definitely look into a UITableView. Apple's documentation for a UITableViewController can be found here https://developer.apple.com/library/ios/documentation/uikit/reference/UITableViewController_Class/Reference/Reference.html
I just have a quick question about recommended ways to implement a master-detail view hierarchy in iOS--the kind where selecting a row in a table on one screen pushes a details view for that item onto the navigation stack.
Specifically, should I reuse the same instance of the details view controller and just change its target and reload it each time, or should I instantiate a new instance of the view controller each time?
I'd prefer the first method, as it just seems generally more efficient, but I'm having trouble figuring out how to set the target and do the reload (especially the first time, when the view controller has not yet even been initialized--I'm using storyboards and that pretty much handles all of the initialization itself).
Or perhaps instead of setting the target on the child view controller, I could set it on the parent, such that each time the child view controller is shown, it reloads itself based on the parent selection? That actually sounds like the best bet so far, just looking for tips/warnings from anyone who's run into this before.
First, there's nothing wrong with creating a new view controller each time. If you use segues, that's what you'll get, since segues always instantiate new controllers. The detail controller will be deallocated when you pop or dismiss it anyway, so it won't persist.
If you want to use the same controller, you have to do your push or presentViewController in code. You can still setup the controller in the storyboard. Give it an identifier, but don't connect it up with a segue. In code, you check for the existence of your controller (you'll need a property for it), and if it doesn't exist, create it.
if (! self.detailController) {
DetailController *dvc = [self.storyboard instantiateViewControllerWithIdentifier:#"MyIdentifier"];
}
self.dvc.whateverProperty = self.somePropertyIWantToPass; // pass some date to it
[self.navigationController pushViewController:dvc animated:YES completion:nil];
I need to create a modal "flow" within my app. It is made of two "scenes", these are both UITableViewController subclasses.
The user will be able to push and pop between these two table views.
At any point they will be able to press "Done" (in a nav bar) and dismiss the entire modal view to go back to where they were.
This whole modal flow needs to be accessible from several places in the app. I don't really want to create multiple modal segues to this.
My question is, creating this in a storyboard, would you create a whole new storyboard for this flow (I don't like this).
Would you just create multiple modal segues?
Should I create this flow in the same storyboard file but as a separate entity accessible by the identifier?
Or something else?
Sounds like it would be easier to use a single storyboard, but not create multiple segues everywhere. You can programmatically present the view controller pretty easily:
MyViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:#"MyViewController"];
// set any properties on vc here, if necessary to pass it any data
[self.window.rootViewController presentModalViewController:vc animated:YES];
You could place all this code in a helper method to reuse this code more easily, maybe a class method like this:
#interface MyViewController ...
+ (void)presentNewViewControllerModally;
...
#end
Tapping the done button:
[self.window.rootViewController dismissModalViewControllerAnimated:YES];
Note that if there's a good chance you'll never see this modal view controller, you could place that view controller in a separate xib file instead of in the storyboard, and I think that could make things more efficient (storyboard remains more lightweight). In this case, just replace the instantiteViewControllerWithIdentifier message above with:
[[MyViewController alloc] initWithNibName:#"SomeNib" bundle:nil];
...and the rest of the code is the same. I've used this technique for a "login" view controller that would only occasionally need to be presented.
I have about 20 View Controllers, chained together with Modal and Push segues. Now, at the last View Controller I want to switch back again to the first View Controller, as if the user has restarted the app. Unfortunately when I do this with
[UIViewController *viewController = [self.storyboard instantiateViewControllerWithIdentifier:#"InitViewController"]];
[self presentViewController:viewController animated:YES completion:nil];
all of the previous view controllers are not unloaded. Not a single viewDidUnload method is called. How can this be done?
The instantiateViewController method creates a new copy of your view controller. Your existing view controllers aren't unloaded because iOS doesn't know that you want to 'go back', so to speak. It can't unload any of your existing view controllers because they're still in the navigation hierarchy. What you really want to do is 'rewind' your storyboard in some way.
Fortunately from iOS 6 there's a much improved way to do this, through unwinding. This lets you 'backtrack' in your storyboard right back to the start, which it sounds like you want to do. The WWDC videos have some examples and walk throughs, and you might also want to look at this existing SO question:
What are Unwind segues for and how do you use them?
I found that it can be done easily by calling dismissViewControllerAnimated:completion: on the first view controller in the hierarchy. Fortunately that's all it is needed to accomplish what I wanted :-)