I am just wondering how I could programmatically navigate around a navigationController stack?
I am familiar with the method:
[self.navigationController popToRootViewControllerAnimated:YES];
as well as:
[self.navigationController popViewControllerAnimated:YES];
But could programatically go to ANY view controller in my navigation controller?
Please see my pic:
http://s18.postimage.org/iq1l4f721/test_xcodeproj_Main_Storyboard_storyboard.jpg?
I know I can segue to any view using the storyboard but am I right in thinking this would keep pushing new views onto the stack and eventually (in theory) I would run into problems?
Thanks
Carl.
Yes , if you know the index of the controller in the stack or if you have a reference to it.
Like this:
[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:index] animated:TRUE];
Cheers!
have you tried
for (UIViewController * viewController in self.navigationController.viewControllers) {
if ([viewController isKindOfClass:[Number2Class class]]) {
[self.navigationController popToViewController:viewController animated:YES];
}
}
Use this code to navigate to the desired viewcontroller
NSArray *vcs = self.navigationController.viewControllers;
for (UIViewController *cont in vcs) {
if([cont class] == [YOUR_VIEWCONTROLLER_NAME class])
{
NSLog(#"Class Found");
}
Have you read UINavigationController Class reference?
UINavigationController has property NSArray *viewControllers, which holds current stack of view controllers (history).
setViewControllers:animated: - Replaces the view controllers currently managed by the navigation controller with the specified items. (overrides history)
popToViewController:animated: - Pops view controllers until the specified view controller is at the top of the navigation stack. (here you will need to pass an instance that exists in the history - see above)
Get back to #1...
Related
I'm working on my first app. Here's what I want to accomplish:
There will be a menu with several different options. For simplicity, assume this is comprised of UIButtons with IBAction outlets and the functionality exists to pull up the menu at any time.
Each menu button, when pressed, should display a different navigation controller's content. If the user brings up the menu and makes a different selection, the navigation controller in which he is currently operating should not be affected; the newly selected navigation chain is displayed on top of the old, and through the menu, the user can go back to the view where he left off on the previous navigation chain at any time.
visual illustration (click for higher resolution):
Please note that there are 3 different navigation controllers/chains. The root view controller (which is also the menu in this simplified version) is not part of any of them. It will not suffice to instantiate one of the navigation chains anew when it has been previously instantiated, and here's why: if the user was on screen 3 of option 2 and then selects option 1 from the menu and then selects option 2 (again) from the menu, he should be looking at screen 3 of option 2--right where he left off; the view controller he was viewing when he previously left the navigation chain should be brought back to the top.
I can make a button instantiate and present a view controller from the storyboard if there is NOT a navigation controller:
- (IBAction)buttonPressed:(id)sender {
UIViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:#"View 2"];
[self presentViewController:controller animated:YES completion:nil];
}
However, I can't figure out how to make those two methods work with a navigation controller involved. Moreover, I'm not sure those two methods are the right choice, because I won't always want to instantiate a new view controller: when a menu button is pressed, a check should be performed to see if the view (navigation?) controller with the corresponding identifier has already been instantiated. If so, it should simply be made the top view controller.
In summary, here are my questions:
1) How should I instantiate and display a view controller that is embedded in a navigation controller, preferably using a storyboard ID? Do you use the storyboard ID of the navigation controller or of the view controller?
2) How should I check whether an instance already exists? Again, should I check for an extant navigation controller or for a view controller, and what's the best method to do so?
3) If the selected navigation chain has already been instantiated and is in the stack of view controllers somewhere, what is the best method for bringing it to the top?
Thank you!!
side note -- it would be nice to know how to paste code snippets with indentation and color formatting preserved :)
As Rob has suggested, a tab bar controller would make a good organising principle for your design.
Add a UITabBarController to your storyboard, give it a storyboard iD. Assign each of your three sets of viewControllers ( with their respective navController) to a tab item in the tabBarController.
UITabBarController
|--> UINavigationController --> VC1 ---> VC2 -->
|--> UINavigationController --> VC1 ---> VC2 -->
|--> UINavigationController --> VC1 ---> VC2 -->
In you app delegate make a strong property to hold your tab bar controller's pointer. As the tab bar controller keeps pointers to all of it's tab items, this will take care of state for each of your sets of viewControllers. You won't have to keep separate pointers for any of them, and you can get references to them via the tabBarController's viewControllers property.
#property (strong, nonatomic) UITabBarController* tabVC;
Initialise it on startup
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
UIStoryboard storyBoard =
[UIStoryboard storyboardWithName:#"MainStoryboard_iPhone" bundle:nil];
self.tabVC = [storyBoard instantiateViewControllerWithIdentifier:#"tabVC"];
//hide the tab bar
for (UINavigationController* navController in self.tabVC.viewControllers)
[navController.viewControllers[0] setHidesBottomBarWhenPushed:YES];
return YES;
}
An alternative way to hide the tab bar is to check the "Hides bottom bar on push" box in the Attributes Inspector for each of the (initial) viewControllers. You don't have to do this for subsequent viewControllers, just the first one that will be seen in that tab item.
Then when you need to navigate to one of your navController groups…
- (IBAction)openTab:(UIButton*)sender {
AppDelegate* appDelegate =
(AppDelegate*)[[UIApplication sharedApplication] delegate];
if ([sender.titleLabel.text isEqualToString: #"Option 1"]) {
appDelegate.tabVC.selectedIndex = 0;
}else if ([sender.titleLabel.text isEqualToString: #"Option 2"]){
appDelegate.tabVC.selectedIndex = 1;
}else if ([sender.titleLabel.text isEqualToString: #"Option 3"]){
appDelegate.tabVC.selectedIndex = 2;
}
[self presentViewController:appDelegate.tabVC
animated:YES completion:nil];
}
(this example uses presentViewController, your app design may navigate this in other ways…)
update
If you want to do this without a tab bar controller, you can instantiate an array holding pointers to each of your nav controllers instead:
UINavigationController* ncA =
[storyboard instantiateViewControllerWithIdentifier:#"NCA"];
UINavigationController* ncB =
[storyboard instantiateViewControllerWithIdentifier:#"NCB"];
UINavigationController* ncC =
[storyboard instantiateViewControllerWithIdentifier:#"NCC"];
self.ncArray = #[ncA,ncB,ncC];
Which has the benefit of not having a tab bar to hide…
Then your selection looks like…
- (IBAction)openNav:(UIButton*)sender {
AppDelegate* appDelegate =
(AppDelegate*)[[UIApplication sharedApplication] delegate];
int idx = 0;
if ([sender.titleLabel.text isEqualToString: #"option 1"]) {
idx = 0;
}else if ([sender.titleLabel.text isEqualToString: #"option 2"]){
idx = 1;
}else if ([sender.titleLabel.text isEqualToString: #"option 3"]){
idx = 2;
}
[self presentViewController:appDelegate.ncArray[idx]
animated:YES completion:nil];
}
1 / You can instantiate a viewController in your viewDidLoad method of your main viewController, so it will be instantiate 1 time only.
Now if you want display your controller, you would better push it :
- (IBAction)buttonPressed:(id)sender {
// Declare your controller in your .h file and do :
controller = [self.storyboard instantiateViewControllerWithIdentifier:#"View 2"];
// Note you can move this line in the viewDidLoad method to be called only 1 time
// Then do not use :
// [self presentViewController:controller animated:YES completion:nil];
// Better to use :
[self.navigationController pushViewController:controller animated:YES];
}
2 / I'm not sure, but if you want to check if an instance already exist just check :
if (controller) {
// Some stuff here
} // I think this checks if controller is initiated.
3 / I know it's not a good advice but I would tell you to not worry about checking if your controller already exist, because I think it's easier to access your viewController by using the 2 lines again :
controller = [self.storyboard instantiateViewControllerWithIdentifier:#"View 2"];
[self.navigationController pushViewController:controller animated:YES];
4 / I'm not sure if colors can be used here because of a specific style sheets.
I'm not sure to really have the good answer to your question but I hope this will help you.
I need a little help on a problem with navigation controllers.
I have a navigationController with 4 ViewControllers pushed. The last vc I push presents a further ViewController modally. The modal ViewController presents an ActionSheet. Depending on the user's answer I either dismiss the modal ViewController only or I want to go back to the root ViewController.
In the ViewController presented modally I have:
- (void) dismissGameReport
{
[[self delegate] GameReportModalWillBeDismissed:modalToPopToRoot];
}
In the last ViewController pushed onto the navigationController stack I have:
- (void)GameReportModalWillBeDismissed: (BOOL)popToRoot;
{
if (popToRoot)
{
[self.navigationController popToRootViewControllerAnimated:NO];
}
else
{
[self dismissModalViewControllerAnimated:YES];
}
}
Dismissing the modal view controller works fine.
However,
[self.navigationController popToRootViewControllerAnimated:NO];
does not cause the root ViewController to display its views. Adding some log info I see that after the message to self.navigationController the stack is correctly popped but execution continues sequentially. The screen still shows the view of the modal ViewController.
As a workaround I tried always dismissing the modal view controller and in the ViewWillAppear method have the popToRootAnimated message. No difference. Still the stack of controllers is popped but the screen continues showing my modal view controller's view and execution continues sequentially.
Could someone help me please?
I like these deceptive questions. It seems very simple, until you try to do it.
What I found was that basically you do need to dismiss that modal view controller, but if you try to pop from the navigation controller on the next line things get mixed up. You must ensure the dismiss is complete before attempting the pop. In iOS 5 you can use dismissViewControllerAnimated:completion: like so.
-(void)GameReportModalWillBeDismissed:(BOOL)popToRoot{
if (popToRoot){
[self dismissViewControllerAnimated:YES completion:^{
[self.navigationController popToRootViewControllerAnimated:YES];
}];
}
else{
[self dismissModalViewControllerAnimated:YES];
}
}
But I see you have 4.0 in your question tags. The solution I found for <iOS 5 is far less pretty but should still work, and it sounds like you were already on the trail. You want viewDidAppear: not viewWillAppear:. My solution here involves an ivar, lets say:
BOOL shouldPopToRootOnAppear;
And then your GameReportModalWillBeDismissed: would look something like this:
-(void)GameReportModalWillBeDismissed:(BOOL)popToRoot{
shouldPopToRootOnAppear = popToRoot;
[self dismissModalViewControllerAnimated:YES];
}
And your viewDidAppear: would look like this...
-(void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
if (shouldPopToRootOnAppear){
[self.navigationController popToRootViewControllerAnimated:YES];
return;
}
// Normal viewDidAppear: stuff here
}
First off, I am aware of this question being asked in a forward manner, but in this case I am asking for a backwards manner in which the Navigation Controller is already designed. With that being said...
I have a UINavigationController with three views: Table, Get, and Avail in that order that was created in IB.
When going forward, I want to go from Table to Get to Avail, but when I hit the "Back" button on Avail I want to skip over Get and go directly back to Table. Is this possible? If so, how?
Here's how I did it:
NSArray *VCs = [self.navigationController viewControllers];
[self.navigationController popToViewController:[VCs objectAtIndex:([VCs count] - 2)] animated:YES];
To be able to override the nav controllers's back button you're going to have to subclass UINavigationController. Check out how in this tutorial: http://www.hanspinckaers.com/custom-action-on-back-button-uinavigationcontroller
Implement the navigation controller's delegate method:
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
It will fire for all VCs in the nav controller stack. (put this code in the VC immediately after your navigation controller, and put < UINavigationControllerDelegate > in the .h)
What you want to do is replace the entire Navigation Controller's stack without the view controller you want to remove in it. Since it's a non-mutable array, you have to convert it to a mutable array before removing the VC, remove the VC, then replace the navigation controller's stack with the call [self.navigationController setViewControllers:newVCs animated:NO];. That's the crucial part. You are replacing the stack after you have loaded the page you are on but since you're keeping the VC you're on, it's still the top item on the stack so there is no visible impact to the user. As long as you don't have a lot of VCs on the stack, it's not an expensive call.
Here's how I did it in the delegate method:
//Remove list setup page if new list was created
if ([self.navigationController topViewController].class == [ItemViewController class])
{
NSArray *VCs = [self.navigationController viewControllers];
if(((UITableViewController*)[VCs objectAtIndex:[VCs count]-2]).class == [NewCardTypeController class])
{
NewCardTypeController *removedObject = [VCs objectAtIndex:[VCs count]-2];
if(removedObject != nil)
{
NSMutableArray *newArray = [NSMutableArray arrayWithArray:VCs];
[newArray removeObject:removedObject];
NSArray *newVCs = [NSArray arrayWithArray:newArray];
[self.navigationController setViewControllers:newVCs animated:NO];
}
}
}
Take a look at UINavigationController's -popToViewController:animated: and -popToRootViewControllerAnimated:, which do exactly what you're asking for. That is, they pop the navigation stack back to a particular view controller, or to the root view controller. You'll still need to intercept the nav controller's back button action to use them, though.
I have a main UITableView, when cell is pressed it goes to another UITableView and when a cell is pressed there it goes to a DetailView of that cell.
I want the middle UITableView to behave differently depending on if the detailView got popped or the UITableView itself got pushed. If the view got pushed on from the main table I want to scroll to the top, if it is shown after a DetailView got popped I want it to stay at the same position.
Any suggestions?
you could call a scrollToTop method on the DetailViewController after you have pushed it to the navigationController.
Something like that:
if (!detailViewController) {
detailViewController = [[DetailViewController alloc] initWithNibName:nil bundle:nil];
}
[self.navigationController pushViewController:detailViewController animated:YES];
[detailViewController scrollToTop];
// or use the tableView directly:
// [detailViewController.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
In your Middle View Controller, examine which view is next-to-display directly from the UINavigationController stack:
- (void)viewWillDisappear:(BOOL)animated
{
if ([self.navigationController.topViewController isEqual:(UITableViewController *)tvcDetailView]) {
// Detail view has been pushed onto the UINavigationController stack
}
else {
// Middle view has been popped from the UINavigationController stack
}
}
Create a BOOL #property on your middle UIViewController property called wasPushed or something similar, and when you initialise it from UIViewController 1, set the property on the new instance, push it onto the nav stack and you can then use your property in your middle view controller's loadView, viewDidLoad, viewWill/DidAppear methods.
As soon as you've used it, set it back to FALSE or NO (or whatever) and when you end up coming back to it due to popping off your 3rd view controller you'll have it as FALSE/NO in your loadView, viewDidLoad etc.. methods.
I just came across a crash showing a NSInvalidArgumentException with this message on an app which wasn't doing this before.
Application tried to present modally an active controller
UITabBarController: 0x83d7f00.
I have a UITabBarController which I create in the AppDelegate and give it the array of UIViewControllers.
One of them I want to present modally when tapped on it. I did that by implementing the delegate method
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
If that view controller is of the class of the one I want to present modally, I return NO and do
[tabBarController presentModalViewController:viewController animated:YES];
And now I'm getting that error, which seems to mean that you can't present modally a view controller that is active somewhere else (in the tabbar...)
I should say I'm on XCode 4.2 Developer Preview 7, so this is iOS 5 (I know about the NDA, but I think I'm not giving any forbidden details). I currently don't have an XCode installation to test if this crashes compiling against the iOS4 SDK, but I'm almost entirely sure it doesn't.
I only wanted to ask if anyone has experienced this issue or has any suggestion
Assume you have three view controllers instantiated like so:
UIViewController* vc1 = [[UIViewController alloc] init];
UIViewController* vc2 = [[UIViewController alloc] init];
UIViewController* vc3 = [[UIViewController alloc] init];
You have added them to a tab bar like this:
UITabBarController* tabBarController = [[UITabBarController alloc] init];
[tabBarController setViewControllers:[NSArray arrayWithObjects:vc1, vc2, vc3, nil]];
Now you are trying to do something like this:
[tabBarController presentModalViewController:vc3];
This will give you an error because that Tab Bar Controller has a death grip on the view controller that you gave it. You can either not add it to the array of view controllers on the tab bar, or you can not present it modally.
Apple expects you to treat their UI elements in a certain way. This is probably buried in the Human Interface Guidelines somewhere as a "don't do this because we aren't expecting you to ever want to do this".
I have the same problem. I try to present view controller just after dismissing.
[self dismissModalViewControllerAnimated:YES];
When I try to do it without animation it works perfectly so the problem is that controller is still alive. I think that the best solution is to use dismissViewControllerAnimated:completion: for iOS5
In my case i was trying to present the viewController (i have the reference of the viewController in the TabBarViewController) from different view controllers and it was crashing with the above message.
In that case to avoid presenting you can use
viewController.isBeingPresented
!viewController.isBeingPresented {
// Present your ViewController only if its not present to the user currently.
}
Might help someone.
The same problem error happened to me when I tried to present a child view controller instead of its UINavigationViewController parent
I had same problem.I solve it. You can try This code:
[tabBarController setSelectedIndex:1];
[self dismissModalViewControllerAnimated:YES];
For React Native Developer - Problem might not be in AppDelegate Or main.m if app has been successfully build and is running and will crash after splash or perhaps the error screen
Issue might be due to use of fonts/resources that is not available with xcode and not properly configured.. You can find out the error by commenting certain portion starting from App.js and drilling inside the navigation/screens and commenting the components till you find the component that is generating the error....
In my case the resource of fontFamily was making an issue which was used right after splash in walkthrough screen
<Text style={{fontFamily: Fonts.roboto}}>ABC</Text>
Here font roboto wasnot configured properly. Wasted entire days just debugging the error hope its helps you
In my case, I was presenting the rootViewController of an UINavigationController when I was supposed to present the UINavigationController itself.
Just remove
[tabBarController presentModalViewController:viewController animated:YES];
and keep
[self dismissModalViewControllerAnimated:YES];
Instead of using:
self.present(viewControllerToPresent: UIViewController, animated: Bool, completion: (() -> Void)?)
you can use:
self.navigationController?.pushViewController(viewController: UIViewController, animated: Bool)
This is my way which supporting multiple Windows(from a single APP) on the iPad and nested modal present.
import UIKit
///✅Use this public method
public func SheetViewController(ViewController:UIViewController) {
for i in returnAvailableViewControllers().shuffled() {
if i.presentedViewController == nil && !ViewController.isViewLoaded {i.present(ViewController, animated: true, completion: {})}
}
}
///Returns all possible ViewControllers
private func returnAvailableViewControllers() -> [UIViewController] {
let 场景 = UIApplication.shared.connectedScenes
var 存储VC : [UIViewController] = []
for i in 场景 {
if i.activationState == .foregroundActive {
//⭐️Set up “foregroundActive” to give the user more control
var 视图控制器 = (i.delegate as? UIWindowSceneDelegate)?.window??.rootViewController
if 视图控制器 != nil {
存储VC.append(视图控制器!)
}
var 结束没 = true
while 结束没 {
//🌟Enumerate all child ViewController
视图控制器 = 视图控制器?.presentedViewController
if 视图控制器 != nil {
存储VC.append(视图控制器!)
} else {
结束没.toggle()
}
}
}
}
return 存储VC
}