I've been wrestling with this for almost 2 hours now and no luck.
I have a View Controller. Lets call it First. I press a button and it takes me to Second view controller using a modal style. In Second I add some data which I can save or discard via two navigation bar buttons: Save and Cancel. both do what they do and then they return me to the previous screen. I implemented a protocol and I use the delegate. So far everything works fine.
Today I decided to have a Third View Controller which can be accessed from the Second VC. The problem is I couldn't move to THIRD until I changed the transition from First to Second to PUSH (instead of modal). Now I can go from First to Second and from Second to Third. All good again.
THE PROBLEM : If I press Cancel or Save on the Second VC, it calls the methods, it uses the delegate to go to FIRST and execute some function but when it calls:
[self dismissViewControllerAnimated:YES completion:nil];
nothing happens and Im stuck on the Second view. Basically I was using MODAL with Delegate and protocol methods... I switched to PUSH, and I cant get rid of my Second view and return to First. It seems like the dismissViewController doesnt do anything.
Any help is greatly appreciated. I can fix all this by removing the cancel button and using the BACK which comes by default with PUSH but I just want to know what the problem is with it.. THANK YOU !!
On your 2nd viewContrller call the UINavigationController's method popViewControllerAnimated: or popToRootViewControllerAnimated:. This will pop the controller (the one calling, which is the 2nd) off the nav stack. You can get the navigation controller in a UIViewController via its property navigationController.
Related
i am trying to switch between two view controllers using storyboard. I create a modal seague by control-dragging (on buttons) from 1st view controller to 2nd, and then from the 2nd to the first.
So whenever I click on a button in 1st VC, it takes me to the 2nd VC. This time when i click the button on second VC, does it take me back to the original instance of the 1st VC or it creates a new instance?
If it takes me to the same instance, and user had written some data in some textfields, is there anyway to retain that on screen? (I might want to save them in some variables, and since the program will return back to the same instancem i'll be able to get the variables back)
If it doesn't take me to the same instance, is there any method to do so?
I tried making an instance of 2nd VC and using self.navigarionController push...(instance) but this doesn't swtich the controller.
If i do this pushing using the storyboard, and i do pop in my 2nd VC, it doesn't get popped either.
(and i would also couldn't understand the difference between push,modal and custom seagues)
Create the modal segue from VC1's button to VC2, but not the reverse one. When the VC2's button is tapped, call dismissViewControllerAnimated:completion: to return to where you were.
If you used a push segue instead, you would call popViewControllerAnimated: to go back but that only works if you have your view controllers managed by a UINavigationController.
You can think of push as a way of stepping through a sequence of related scenes while modal is something that's a bit out of the normal flow of the application. (That's not a firm rule but it's a starting point for deciding which way to go.) For 'custom', you write the segue code, so you decide what happens.
(Apologies for not being able to embed my images yet).
Using iOS storyboards, I have a UITabBarController with a UINavigation Controller/UITableView(1) embedded in it. This UITableView(1) then calls another UITableView(2):
What I'm trying to do is to make UITableView(2) appear when the Tab Bar is changed to that tab, and then have the UINavigationBar left arrow button exist to get back to UITableView(1).
The existing functionality I can think of which does this is the iPhone Mail app, where when you launch it you see your Inbox, and you can hit the left-arrow Mailboxes button to get back to your mail box list.
I've tried attaching the tab bar directly to UITableView(2) but it doesn't work as expected, there's no left arrow back button to get back to the previous view when the app is run.
I've also tried adding a navigation controller to that UITableView(2) and the Navigation controller correctly appears, but still without any back button:
Any suggestions as to what I'm doing wrong would be greatly appreciated, I'm fairly new with storyboards and it's difficult to find what to search to get this working.
If it's not possible with just storyboards themselves, is there some kind of automatic (non-visible) push to the 2nd UITableView I could do?
Thanks!
Nick.
This tutorial will definitely help you : http://maybelost.com/2011/10/tutorial-storyboard-in-xcode-4-2-with-navigation-controller-and-tabbar-controller-part1/
I ended up implementing it the following way, as I wanted to perform the majority of the work within storyboards.
I set up the storyboard with the tab bar embedding the UINavigationController, which contained UITableView(1) which then contained a custom segue to UITableView(2):
Then within the class associated with UITableView(1) I added this single line:
- (void)viewDidLoad {
[self performSegueWithIdentifier:#"campaigns" sender:self];
...
}
On load of the tab, the viewDidLoad of UITableView(1) instantly calls UITableView(2) without any kind of animation, showing the back button to UITableView(1), which is exactly what I wanted.
Thanks to those who responded!
You can implement the delegate method as below.
(void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
In this method you can check for the tabBarController.selectedIndex or viewController object. This ensures the selection of correct tab , then push the controller having table 1, then push the controller having table 2.
New to iOS, kindly bare if the question is very basic? When I press the tab button multiple times, it is not invoking viewWillAppear function? If I am wrong, then which function gets invoked, each time a tab button is pressed being on the same tabview?
You are correct, viewWillAppear is a little special, it is usually called automatically but in some cases including when you are adding a view controllers view manually (view addSubview:), and also when adding this as a view controller to a UITabViewController it doesn't get messaged.
This however is only for the root view, as you navigate (maybe with a navigation controller) back and forth, that root view's viewWillAppear will get triggered as some point.
In short, if you need to implement something in viewWillAppear in these cases, you should message it yourself when you know it's going to be presented. You can handle this case in your view controller, check out the following article about the matter:
http://www.touchthatfruit.com/viewwillappear-and-viewdidappear-not-being-ca
Good luck.
In the view controller that has a UITabBarItem, i realized that viewDidLoad() method only gets called the first time when the tab bar item is clicked. So I dont know how to bring up the dynamic graphics when it's clicked the 2nd time. Can some guru help me on this? thanks in advance.
Should I conform to some kind of delegates or should i do it within didSelectViewController method on the root controller of all the tab bars? If i do the later one, it just seems to be weird since i think the controller that has the corresponding tab bar item should render itself instead of doing the rendering on root controller..
You want to put any code that should run every time the view controller appears in viewWillAppear: instead of viewDidLoad. viewDidLoad is designed for code that should run when the view backed by your UIViewController is created (and then possibly re-created after being thrown away during low-memory situations).
Actually i resolved this by using the parameter passed into the callback didSelectViewController(param).
I am writing an application(for iPhone) that uses the UINavigationController to show different view via pushViewController. I am trying to push multiple UIViewController immediately upon application startup without user interaction. When an user open up the application, they will be looking on a screen with a navigation bar on the top that already have a back button.
The problem I am experiencing is that viewWillDisappear and viewDidDisappear of a ViewController does not always get call if another ViewController is pushed on top of it immediately upon application start up without user interaction. If the ViewController being pushed on top is activate by the user with a button click, then viewWillDisappear and viewDidDisappear of the view being cover always get call.
Note. viewWillAppear and viewDidAppear of the covered view controller always get called.
In the code that is experiencing the problem, I am pushing the new view controller in viewDidAppear of the previous ViewController.
Anyone know what I might be doing wrong or if the behavior I am seeing is expected?
The problem I am experiencing is that viewWillDisappear and viewDidDisappear of a ViewController does not always get call if another ViewController is pushed on top of it immediately upon application start up without user interaction.
Sound pretty sensible to me. After all, the "covered" view never appeared on screen, so it cannot disappear. I would expect this behavior.