I need to perform a segue from my storyboard. The method to call in that case is -[UIViewController performSegueWithIdentifier:sender:]. This method relies on the storyboard property of UIViewController to find the storyboard (and therefore the segue).
However, the storyboard property is not set when the UIViewController was not created from the storyboard. And since it's read-only, I can't set it programmatically where I load my storyboard.
So the question is: how to perform a segue from a storyboard that has been loaded programmatically?
If it's not possible, it's perhaps because my architecture is incorrect. Here is the use case:
The app is a legacy tabbar application where each of the 8 tabs has its own NIB file. Many of the 8 tabs are rather complex, and can benefit a lot from storyboards, especially prototype table cells and static tables. So I want to evolve the app to use storyboards.
However, one humongous storyboard doesn't seem a good idea: it would prevent incremental changes to the app, it would be unwieldy, it would make it difficult for the team members to work on their tab independently.
The right level of modularity seems to let the UITabBarController have its own specific storyboard. This makes it possible for each tab to evolve at its own pace and makes it easier for each developers to work on their tab with few source control conflicts.
My approach so far is the main nib file to contain the UITabBarController and each of its main daughter view controllers. The daughter view controllers load their storyboard from their viewDidLoad method. And from there, they can't perform their segue.
The alternative would be for the daughter view controllers to be created from their storyboards, but then how can I hook them up to the UITabBarController? And where do I programmatically load the storyboards?
Thanks for any suggestion.
make a reference on the segue and save the pointer value in a singleton class. Then using the pointer reference saved in the singleton class, access the segue wherever you like and load it. Here is a sample code in which i am loading a segue view from a single storyboard class but each view has separate view controllers .h and .m files that have appropiate connections. (i used formal protocol, hence the line shareVC.delegate = self; is there .
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue isKindOfClass:[UIStoryboardPopoverSegue class]]) {
if (self.currentPopover != nil) {
[_currentPopover dismissPopoverAnimated:YES];
self.currentPopover = nil;
}
UIStoryboardPopoverSegue *popSegue = (UIStoryboardPopoverSegue *)segue;
self.currentPopover = popSegue.popoverController;
}
if ([segue.identifier compare:#"ShareModal"] == NSOrderedSame) {
//the share controller is being presented modally, probably iphone
UINavigationController *shareNavController = segue.destinationViewController;
myViewController *shareVC = (myViewController *)[shareNavController topViewController];
shareVC.delegate = self;
} else if ([segue.identifier compare:#"SharePopover"] == NSOrderedSame) {
FollowersViewController *followerVC = segue.destinationViewController;
followerVC.delegate = self;
} else if ([segue.identifier compare:#"StartScreenSegue"] == NSOrderedSame) {
UINavigationController *startNavController = segue.destinationViewController;
StartViewController *startVC = (StartViewController *)startNavController.topViewController;
startVC.delegate = self;
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationOpenUrlNotification object:nil];
}
}
Hope this helps:)
Related
I'm transitioning my app to iOS 8, and I've decided to use a SplitViewController because its new functionality finally allows me to do what I want. I present the SVC modally on iPad, and the SVC is the root view controller of the full-screen cover vertical transition. From the presenting view controller:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
plotSplitViewController = segue.destinationViewController;
plotViewController = (PlotViewController *)[[[segue.destinationViewController viewControllers] objectAtIndex:1] topViewController];
plotViewController.inventory = _inventory;
if ([plotViewController view]) [plotViewController setPlot:selectedPlot];
}
Then I manually make connections in the PlotSplitViewController:
- (void)viewDidLoad
{
[super viewDidLoad];
self.delegate = self;
// set up controllers
layoutNavigationController = [self.viewControllers objectAtIndex:1];
plotViewController = (PlotViewController *)[layoutNavigationController topViewController];
plotViewController.delegate = self;
// configure split view
[self showInfoPane:NO withTable:infoTableViewController];
self.preferredDisplayMode = UISplitViewControllerDisplayModePrimaryHidden;
}
So both the master and the detail get view controllers inside UINavigationControllers (to take advantage of the free toolbar resizing, plus the master pushes a table view hierarchy).
Everything seems fine; the views load as they're supposed to, the delegate method from PlotViewController functions correctly, etc. But as you can see, I assign the Split View Controller to be its own delegate...but it won't respond to any of its own methods, so I can't customize its behavior. I checked to make sure it's set correctly:
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
NSLog(#"split view %# did appear, delegate: %#", self, self.delegate);
}
And it returns the same object (itself) for both values. Is this just a no-no? I read that you can assign a SplitViewController as its own delegate, and I think an object can be a delegate for more than one other object, right? It can certainly implement protocols for more than one. So why is my SplitViewController not able to receive delegate methods for itself? I have NSLogs in all of them, and none are ever called.
Turns out it works if you make your custom view controller a subclass of UIViewController, and add a UISplitViewController programmatically, as a child view controller. Make your VC its delegate, and you can make it behave however you want.
I have a UIViewController that contains a UITableView. The table view contains a custom UITableViewCell. The custom cell was built in interface builder and has a nib. In my main storyboard, I dragged a segue from the custom table view cell to the destination view controller. I set up the bare bones essentials in prepareForSegue, set a break point, but it never gets called.
I'm not that accustomed to using a UITableView in a view controller. I usually use a UITableViewController, but requirements dictate using the table view in a view controller. My initial assumptions is that most methods of doing things would be nearly identical, but I'm finding that not to be the case.
I tried setting the segue from the view controller itself and using didSelectRowAtIndexPath, and though it worked, the transition to the destination view controller was jerky.
Can anyone suggest what I might be missing in order to cause the prepareForSegue method to fire?
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
GaugeViewController *destination = [segue destinationViewController];
[destination setGaugeID:#"1"];
}
Thanks!
You need to refer to the identity of the segue in the Storyboard, something like this:
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
GaugeViewController *destination = segue.destinationViewController;
if([segue.identifier isEqualToString:#"yourSegue"]) {
NSLog(#"prepareForSegue called");
[destination setGaugeID:#"1"];
}else {
// do something else
}
}
Also don't forget to set the Identifier in the Storyboard.
Remember that push segues are used with Navigation Controllers and a modal segue can be dragged from view controller to view controller.
Is it possible to pass data between storyboards in objective-c with segue when the application is not made from a master detail template?
The only examples I have seen is the one with master detail views.
Yes, it is. You could implement prepareForSegue:sender: in the viewController you are segueing from, like so:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"MySegue"]) {
MyOtherViewController *destination = (MyOtherViewController *)segue.destinationViewController;
destination.someProperty = self.someOtherProperty;
}
}
This will get called before your segue is performed, giving you a hook into the viewController you are segueing to.
Edit:
I didn't realise your ViewControllers were in different Storyboard. This question has already been pretty much answered, here: https://stackoverflow.com/a/9610972/1716763
You wouldn't actually be using a segue though, you would do things programatically and either push your second view controller onto the navigation stack, or present it modally.
I've adapted some of the code from #Inafziger's answer to fit your example:
UIStoryboard *secondStoryBoard = [UIStoryboard storyboardWithName:#"secondStoryBoard" bundle:nil];
MyOtherViewController *myViewController = (MyOtherViewController *)[secondStoryBoard instantiateViewControllerWithIdentifier:#"myOtherViewController"];
myViewController.someProperty = self.someOtherProperty;
[self.navigationController pushViewController:myViewController animated:YES];
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 am trying to open a ViewController from within another ViewController if certain conditions are met. The code seems to run without error but the view is never shown. I am new to xcode 4 /ios 5 so I must be missing something.
Here is the code responsible for opening the second viewcontroller:
CreateUserViewController *createUserController = [[CreateUserViewController alloc] initWithNibName:#"CreateUserView" bundle:[NSBundle mainBundle] keyWrapper:keyChainWrapper];
[self presentViewController:createUserController animated:YES completion:nil];
In my project I have a xib called, "CreateUserView". I have added a view controller to this xib and assigned it to, "CreateUserViewController".
Also I noticed in the apple documentation that is shows setting the delegate of the viewcontroller to be presented. But it seems that no property called, "delegate" is on the viewcontroller object. Is this documentation old? This is the document I am trying to use (section 9-1):
View Controller Programming
Can someone give me a hint? Thanks..
edit Adding Custom Constructor
-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil keyWrapper:(KeychainItemWrapper *)keyWrapper
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if(self){
[self setKeyChainWrapper:keyWrapper];
}
return self;
}
Regarding CreateUserView.xib: you don't want to put a CreateUserViewController object in the nib. You want to set the custom class of the File's Owner placeholder to CreateUserViewController. Then you need to connect the view outlet of File's Owner to the top-level view in the nib.
Regarding the delegate property: The UIViewController class doesn't have its own delegate property. The idea is that you add a delegate property to your subclass of UIViewController. The delegate provides a way for your presented view controller to pass custom information back to the presenting view controller.
Why would you want to do that? Let's consider the code you posted. I'll assume you have a UserListViewController that shows a list of User objects, and has a "Create new user" button. When the user touches the "Create new user" button, you create a CreateUserViewController and present it.
The user interacts with the CreateUserViewController to set the attributes of the new User object - name, rank, hairstyle, etc. Then he touches a "Done" button. Your CreateUserViewController creates the new User object and puts it in the database. Then it needs to dismiss itself, so the UserListViewController's list of User objects will appear again.
But you want the User list to include the newly created User object and you want to scroll the list so that the new User is on the screen. So you need a way to have your CreateUserViewController tell the UserListViewController about the newly created User object. This is where the delegate comes in.
You define a protocol like this:
#protocol CreateUserViewControllerDelegate
- (void)didCreateUser:(User *)user;
#end
and you give your CreateUserViewController a delegate property:
#interface CreateUserViewController
#property (weak, nonatomic) id<CreateUserViewControllerDelegate> delegate;
// ...
When your CreateUserViewController's "Done" button is touched, you notify your delegate of the new User:
- (IBAction)doneButtonWasTouched:(id)sender {
User *user = [self createUser];
[self.delegate didCreateUser:user];
[self dismissViewControllerAnimated:YES completion:nil];
}
In your UserListViewController, you adopt and implement the protocol:
#interface UserListViewController <CreateUserViewControllerDelegate, UITableViewDelegate, UITableViewDataSource>
// ...
#end
#implementation UserListViewController
- (void)didCreateUser:(User *)user {
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:[self.users count] inSection:0];
[self.users addObject:user];
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation: UITableViewRowAnimationAutomatic];
[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition: UITableViewScrollPositionNone animated:YES];
}
and when you need to present a CreateUserViewController, you set the new controller's delegate to the UserListViewController:
- (IBAction)createUserButtonWasTouched:(id)sender {
CreateUserViewController *createUserController = [[CreateUserViewController alloc] initWithNibName:#"CreateUserView" bundle:[NSBundle mainBundle] keyWrapper:keyChainWrapper];
createUserController.delegate = self;
[self presentViewController:createUserController animated:YES completion:nil];
}
In iOS5 the method for pushing new view controllers was really changed around quite a bit from iOS4 and Xcode 3. In summary, storyboards are now used to create your application view controller flow. Even though you may use standalone .xib files to build an application it is much less common in iOS5.
Anyway, the main method for pushing new view controllers onto the screen is done using segues. Check out this tutorial for an introduction: http://www.raywenderlich.com/5138/beginning-storyboards-in-ios-5-part-1
It does a good job on explaining how to create a storyboard and use segues. You can still present view controllers in code "the old way" but it is much much less common now with the introduction of these new technologies. There are also some absolutely awesome tutorials on iTunes U - search for CS193P. It's the Stanford Introductory class to Objective-C and programming for iOS. This should get you started and maybe help you think of a way to push your createUserController in a way more up to speed with iOS5.
UPDATE
I just wanted to add. If you configure your program to use storyboards and segues you can use the method performSegueWithIdentifier:sender: to perform the segue to your createUserController view if the proper conditions are met. See the Apple API for UIViewController for information on how to use this method.