I have two View Controllers: LevelSelectViewController and GameViewController.
Neither are the root view controller for the app I am making (the root view controller is called MainViewController).
How can I use the navigation method pushViewController:animated: for this transition for LevelSelectViewController to GameViewController?
In my LevelSelectViewController, you click a button and the following action method performs:
- (IBAction)buttonPressed:(id)sender {
// the pushViewController:animated: method hopefully can be used
// other code
}
How can I use the navigation method pushViewController:animated: for this transition for LevelSelectViewController to GameViewController?
The term "root view controller" can be a little confusing because UIWindow has a rootViewController property, and UINavigationController has a initWithRootViewController parameter. If you're calling -pushViewController:animated:, you must have a navigation controller in your view controller graph since that method belongs to UINavigationController. If your LevelSelectViewController instance is part of a navigation stack, you can do this:
- (IBAction)buttonPressed:(id)sender {
// create a game controller
GameViewController *gameController = [[GameViewController alloc] initWithNibName:nil bundle:nil];
// push it
[self.navigationController pushViewController:gameController animated:YES];
// other code
}
A more typical thing to do these days, though, is to put all the view controllers in a storyboard and simply connect the button to a push transition.
If you're using storyboards just create a segue. If you're not passing any information you can push to it by control dragging from one view controller to another. It doesn't matter if it's the root view controller or not.
If you want to pass data create a segue on storyboards from the view controller, not the index path or button etc. and invoke the prepareForSegueMethod in the view controller with the exact same identifier as the segue on storyboards.
Related
I'm experiencing a memory leak (the UINavigationController and its root View Controller are both being leaked) when presenting and dismissing a UINavigationController in a subview. My method of presentation of the navigation controller seems a bit non-standard, so I was hoping someone in the SO community might be able to help.
1. Presentation
The Navigation Controller is presented as follows:
-(void) presentSubNavigationControllerWithRootViewControllerIdentifier:(NSString *)rootViewControllerIdentifier inStoryboardWithName:(NSString *)storyboardName {
// grab the root view controller from a storyboard
UIStoryboard * storyboard = [UIStoryboard storyboardWithName:storyboardName bundle:nil];
UIViewController * rootViewController = [storyboard instantiateViewControllerWithIdentifier:rootViewControllerIdentifier];
// instantiate the navigation controller
UINavigationController * nc = [[UINavigationController alloc] initWithRootViewController:rootViewController];
// perform some layout configuration that should be inconsequential to memory management (right?)
[nc setNavigationBarHidden:YES];
[nc setEdgesForExtendedLayout:UIRectEdgeLeft | UIRectEdgeRight | UIRectEdgeBottom];
nc.view.frame = _navControllerParentView.bounds;
// install the navigation controller (_navControllerParentView is a persisted IBOutlet)
[_navControllerParentView addSubview:nc.view];
// strong reference for easy access
[self setSubNavigationController:nc];
}
At this point, my expectation is that the only "owner" of the navigation controller is the parent view controller (in this case, self). However, when dismissing the navigation controller as shown below, it is not deallocated (and as a result its rootViewController is also leaked, and so on down the ownership tree).
2. Dismissal
Dismissal is pretty simple, but it seems not to be sufficient for proper memory management:
-(void) dismissSubNavigationController {
// prevent an orphan view from remaining in the view hierarchy
[_subNavigationController.view removeFromSuperview];
// release our reference to the navigation controller
[self setSubNavigationController:nil];
}
Surely something else is "retaining" the navigation controller as it is not deallocated. I don't think it could possibly be the root view controller retaining it, could it?
Some research has suggested that retainCount is meaningless, but FWIW I've determined that it remains at 2 after dismissal, where I would expect it to be zero.
Is there an entirely different / better method of presenting the subNavigationController? Maybe defining the navigation controller in the storyboard would have greater benefit than simply eliminating the need for a few lines of code?
It is best practice when adding a controller's view as a subview of another controller's view, that you make that added view's controller a child view controller; that is, the controller whose view your adding it to, should implement the custom container controller api. An easy way to set this up is to use a container view in the storyboard which gives you an embedded controller automatically (you can select that controller and, in the edit menu, choose embed in Navigation controller to get the UI you're trying to make). Normally, this embedded view controller would be added right after the parent controller's view is loaded, but you can suppress that by implementing shouldPerformSegueWithIdentifier:sender:. I created a simple test app with this storyboard,
The code in ViewController to suppress the initial presentation, and the button methods to subsequently present and dismiss it is below,
#implementation ViewController
-(BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender {
if ([identifier isEqualToString:#"Embed"]) { // The embed segue in IB was given this identifier. This method is not called when calling performSegueWithIdentifier:sender: in code (as in the button method below)
return NO;
}else{
return YES;
}
}
- (IBAction)showEmbed:(UIButton *)sender {
[self performSegueWithIdentifier:#"Embed" sender:self];
}
- (IBAction)dismissEmbed:(UIButton *)sender {
[[self.childViewControllers.firstObject view] removeFromSuperview];
[self.childViewControllers.firstObject willMoveToParentViewController:nil];
[self.childViewControllers.firstObject removeFromParentViewController];
}
#end
The navigation controller and any of its child view controllers are properly deallocated when the Dismiss button is touched.
The navigationController property on a UIViewController is retain/strong, which is presumably the other strong reference.
So try popping all view controllers from the navigation controller and see if that works.
I have a view controller. When I press a button in it, a popover controller with a uitableview shows up. I select a row, which shows another view with some controls in it. When I press a button that says "Save Item", I want it to dismiss the popover. How do I do this?
Here's what I've tried:
Using the delegate and protocol pattern. This hasn't worked since in order to push another view inside my tableview, the whole thing must be embedded in a navigation view controller, so when I segue, it segues to a nav controller, not the tableview which I could set the popover delegate for.
Adding my main view as a member of the view I want to dismiss from. I don't know why this doesn't work.
The Hard Clean Way
There are four view controllers in the story, plus a popover controller. I will call the three view controllers "main view controller", "nav", "vcA", and "vcB". As I understand it, "nav" is the initial content view controller of the popover and has "vcA" as its root view controller.
main view controller -> popover controller -> nav -> vcA -> (later) vcB
When you present the popover from your main view controller, you keep a reference to the popover controller. This is what makes dismissing possible, as you know.
When you create the Save button, you make its target the main view controller and its action a method in the main view controller. You will have to set this up in code; it cannot be configured from a storyboard because you cannot form an action from one scene to another. (You are able to do this because you started out with a reference to nav and vcA when you configured the popover controller initially. Thus you can hand vcA a reference to self, the main view controller. If necessary, you can then pass this reference down the chain from vcA to vcB as vcB is summoned and pushed onto the navigation stack.)
Now the user taps Save, your main view controller's method runs, and it uses its reference to the popover controller to tell it to dismiss.
The Easy Dirty Way
The heck with all that. The main view controller registers for an NSNotification. The Save button posts that NSNotification. Done. :)
The Middle Way
You could set the whole chain up in your storyboard using a popover segue, and do the dismissal through an Unwind segue matched by an unwind method back in the main view controller. I never think of this initially, because I don't like popover segues very much. But it does work.
This is how I solved my problem (sorry for the bad english):
First, Create a property of UIStoryboardPopoverSegue in the VcA and set it from the main view controller.
Nav -> VcA_ViewController
#property (strong, nonatomic) UIStoryboardPopoverSegue *popupSegue;
Then, in the Main View Controller prepareForSegue set the property:
- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if([segue.identifier isEqualToString:#"your segue from the mainview to the navigation"]) {
UINavigationController *navigationController = (UINavigationController *)c;
VcA_ViewController *vcA = (VRPointOfInterestsFiltersViewController *) navigationController.topViewController;
vcA.popupSegue = (UIStoryboardPopoverSegue*)segue;
} }
Now, from the VcA controller you can have the dismiss button
- (IBAction)dismissPopoup:(id)sender {
[self.popupSegue.popoverController dismissPopoverAnimated:YES]; }
Don't forget to link the popOverSegue from the MainViewController to the NavController.
Hope it helps!
I have a regular UINavigationController with a couple of views attached, which are working perfectly fine. Its RootViewController has a custom Menu-button on the top left, at the same place as the "Back"-button is on the attached views. When clicking this menu-button, the menu appears and presents five options.
Obviously, by clicking one of these option, you would be presented with the ViewController for that option.
I want to completely 'forget' the current ViewController, and move on to this new controller. Usually, I would do something like [self presentViewController....]; or [self.navigationController push..];, but in these methods the current ViewController will, I think, always exists 'below' the new presenting viewController (as you would return to this instantiation if using [self dismissViewController..];, I don't want this).
In the presenting ViewController there will be a menu-option to return back to the original controller, but I still want this to be a clean instantiation of it, and not just popping. By thinking ahead in time, I figured I would potentially create an infinite number of ViewControllers on top of each other by using the methods I know of this way.
I entered the world of iOS after the era of ARC began, so I have no clue how to release or deallocate such views, which I assume has relevance here.
The second View Controller is also supposed to be a root in a UINavigationController, and I'm not sure if it's best to use the same UINavigationController, or if I should present a new one, and dismiss the old. Essentially, I would like to replace the Navigation Controller's rootViewController from the rootViewController, but I don't see how that would be possible. Or possibly push to ViewController2, and then popping the rootViewController out of the hierarchy, leaving the new ViewController as the root, but then I assume I'd have problems with the navigational back-button(if it's even possible).
I figured it's just as easy to let ViewController2 be root at its own NavigationController, and presenting this NavigationController from ViewController1. The problem is, I want to completely remove everything that has to do with ViewController1 and its NavigationController from memory after presenting ViewController2, but I have no idea how.
I'm open to other solutions to my situation, but I'd also like an answer to how I can completely 'forget' a view after presenting another on general basis.
If you want to "forget" controllers, you can just replace the window's root view controller with a new one. The original one will be deallocated if you don't have any other strong pointers to it. I'm not sure I understand all of what you're trying to do, but for example, if you want controller 1 and controller 2 to both be root view controllers of a navigation controller, and you don't want controller 1 around when you switch to 2, then do something like this from controller one:
SecondViewController *second = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:second];
self.view.window.rootViewController = nav;
This will switch out the controllers, and controller 1 and its navigation controller will be deallocated (assuming that the only thing with a strong pointer to the navigation controller was the window, through its rootViewController property).
Create a menu UIViewController and add it as a root to the UINavigationController on launch. Add 1st UIViewController as a child controller to menu UIViewController when viewDidLoad of menu controller is called. When you click menu to show 2nd UIViewController, remove the 1st UIViewController from menu view controller and add 2nd UIViewController to child of the menu view controller. You can put NSLog in both, 1st and 2nd view controller's dealloc method to check if its released or not. Logic is like this
//inside menuvc class
#interface MenuVC{
UIViewController * currentVC; // current child controller to menuVC
}
-(void)viewDidLoad{
[self addChildController:firstVC]; //to add view controller 1 intially
currentVC = firstVC;
}
-(void)add2ndChildController{
[currentVC removeFromParentViewController];
[self addChildController:secondVC]; //to add view controller 2 when needed
currentVC = secondVC;
}
// dealloc of 1st vc
-(void)dealloc{
NSLog(#"first vc released");
}
I just wrote some sample logic of what I explained before, you have to generalize this logic if you feel its right for you. Hope it helps :)
I simply want to add a navigation bar (with some nav bar button) on a presented modal controller with storyboard.
Programmatically with XIBs, it looks like that :
SDMapController *mapController = [[SDMapController alloc] initWithNibName:#"SDMapController" bundle:nil];
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:mapController];
[self presentModalViewController:navigationController animated:YES];
But I have no idea how to handle it with Storyboard. I guess i have to implement some code on the -(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender method but since the destinationController property of segue object is readonly, i don't really know how to do this.
Any idea ?
You have to implement the prepare for segue, only if you want to pass on some data to your presented view controller. Otherwise you can leave it empty. The presenting of the View Controller is from the Interface Builder. You add a navigation controller with it's root view controller and make a segue (ctrl + drag) to the navigation controller. Set the segue type to modal, and give it an ID. You can trigger this segue from code by calling [self perforSegueWithIdentiefier:#"MySegueID"];. If you dragged the segue from a button or a table view cell, it will be triggered automatically when you tap on it, without calling this method. As I said, in the prepareForSegue method, the segue.destinationViewController will bee the presented navigation controller. You can access it's topViewController if you need and pass some data to it.
In my StoryBoard, I have embedded my root view controller inside a Navigation Controller, and this view gets displayed when the app is launched. The user then goes through a series of views, which are basically view controllers presented modally.
I'm trying to implement a function to go back to the root view controller, so I called
-(IBAction)backToMenu{
NSLog(#"Back to menu");
[self.navigationController popToRootViewControllerAnimated:YES];
}
but nothing happens. If I do NSLog(#"%#", self.navigationController"); it prints null, so I guess that's the source of my problem. You can't call popToRootViewControllerAnimated: on a view controller that's been presented modally.
Unless you pass a reference to the root view controller. But is this the right approach? If so, how do you pass a reference to the root view controller? As all my view controllers are instances of a custom subclass of UIViewController, I tried doing inserting this in said class's code :
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
[[segue destinationViewController] navigationController] = [[segue sourceViewController] navigationController];
}
but I get an error saying that navigationController is not assignable.
Any thoughts?
In the documentation for dismissViewControllerAnimated:completion:, it says:
If you present several view controllers in succession, thus building a
stack of presented view controllers, calling this method on a view
controller lower in the stack dismisses its immediate child view
controller and all view controllers above that child on the stack.
This suggests that you should keep a reference to your root view controller (or otherwise notify it) and call this method on it. (There's a similar note on the deprecated dismissModalViewControllerAnimated: in case you're using that.)
Does the class that implements the method -(IBAction)backToMenu inherit from UIViewController? I get thi skind of error when the class where I'm implementing the popToRootViewControllerAnimated inherits from some other class. To hold a reference to the original navigatorController I would:
Declare in the class where backToMenu is implemented, a pointer to a pointer to the navigation controller, something like: UINavigationController *navCon; yo should declare this as a property and then synthesizeit.
So when you instance the ViewController for this class you can do something like:
TheClassViewController *theClassVC = [TheClassViewController alloc] initWithNib:#"TheClassViewController" bundle:nil];
theClassVC.navCon = self.navigationController; // Here is where you pass THE reference
[self.navigationController pushViewController:theClassVC animated:YES];
Just solved it.
The problem was that, in the StoryBoard, the initial view controller was the root view controller and not the Navigation Controller it was embedded in!
Once you set the Navigation Controller as the initial view controller (i.e. drag the arrow so that it points to it), popToRootViewControllerAnimated works like a charm.