I'm writing an iPhone app that is based on a UINavigationController. I'm pulling data from a server that sometime returns bogus links. I open each link by pushing a webview viewcontroller. I want to be able to include some error handling. I know if the link is no good. So I want to be able to pop the webview view controller as soon as I know that my webview has encountered an error.
Currently, I've tried using the following code:
[self.navigationController popViewControllerAnimated:YES];
I then get a Navigation bar with nothing displayed in it, but if I click where the "back" button should be it operates appropriately. The title pops up when I click where the "back" button should be. The view where the viewcontrollers usually display there content is blank white too even though I'm popping back to a UITableViewController.
I've tried this as a workaround:
UINavigationController *nav = self.navigationController;
[self.navigationController popViewControllerAnimated:YES];
[nav.visibleViewController.view setNeedsDisplay];
I've checked the viewControllers array in the UINavigationController and it has the right viewcontrollers in it (ie it has removed the viewcontroller for the webview).
I also tried putting code in the viewWillAppear of the viewcontroller I'm popping back to, but the method is never getting called.
I'm looking for a way to force the UINavigationController to reload the same way that you can call reloadData on a UITableView.
Any help would be greatly appreciated.
I saw something like this on my app where I was using a navigation bar I added in Interface Builder on the root view of a navigation controller and then programmatically creating the nav bar and its subviews for the second view. When I would pop the second view to return to the first view I would hide the self.navigationcontroller bar which would show the white space underneath until the IB nav bar of the previous view appeared. To fix this I decided to stick with programmatically creating all my navbars which fixed the issue for me.
TL;DR - if you are using both IB and programmatically made navbars this can happen when popping views, stick with one or the other for all the navbars yo
Related
My UIViewController calls a function on my rootViewController which then called popToRootViewControllerAnimated to return the view to the rootController. This all works - great!
Unfortunately the UINavigationItem (toolbar at the top) seems to display a mashup of both the rootViewController and the UIViewController that has just been removed.
What do I need to do? What have I done wrong?
The navigation bar doesn't remember changes that were made to it, so when you push a new controller, the navigation bar is altered to give the title of the new view controller, but it doesn't store what was there for the previous view controller.
You will need to recreate the items in the toolbar each time you come back to the view controller that has custom items.
You might be able to do this on viewWillAppear instead of viewDidLoad. I can't recall exactly, but you should recreate custom controls on navigation toolbar because it does not get preserved when a new view controller is pushed.
It seems that calling popToRootViewController from the rootViewController messes things up. TO rectify this I called the following from within the calling UIViewController
[self.navigationController popViewControllerAnimated:YES];
I want to hide tabbarcontroller on one view.
But doing so it is displaying white space and not allowing to put any image or anything else on that place.
So what should I do ?
Put one imageView with your desired image on the view controller where you do not want to show tabBar and hide tabBarController before pushing that view on navigation stack using code like
[viewControllerInstanceWhichIsGoingToPushed hidesBottomBarWhenPushed];
The method is something like this. Then Tab Bar will hide and your imageView with image will be displayed in place of TabBar.
If you add a subview to a hidden view, the subview will also go hidden.
In your case, you can have another view controller with just the activity indicator and display the view controller while the loading operation is done. And, after the loading is over, remove that view controller and show the tab bar controller. An example,
// while loading the content
appDelegate.window.rootViewController = loadingViewController;
// once the loading is over
appDelegate.window.rootViewController = tabbarController;
I have encountered this problem before as well and was not able to get anything to get into the blank space using the normal hierarchy. I got around this problem by adding another level of navigation.
ex:
right now you have at UITabBarController which contains your UIViewControllers.
Instead:
Have another UIViewController as the root and then add the tabbarcontroller onto it either as a modalviewcontroller or as a pushed viewcontroller (if you make your root a navigationcontroller). Then, your rootviewcontroller can freely put views under or over the tabbarcontroller's view, independent of whether the bar is present or not.
I'm having a very strange problem with the UINavigationController.
I found a very similar question here:
UINavigationController not popping UINavigationBar items
but the solution there had to do with the fact that the guy had added a category to NSMutableArray, and I'm not doing anything like that.
In short, the problem is this: I have a navigation controller and I'm pushing a few view controllers on it. Then when the 'back' button is tapped the view controller is popped, but the corresponding navigation item isn't. If I tap back again, then the navigation item is popped.
Besides, it only happens when using the back button from the navigation controller's navigation bar. If I call popViewController explicitly (for example from a button press), it works as expected.
And this only happens on my iPad running OS 3.2, but not on my iPod Touch running OS 3.0 or on the simulator.
I've been trying to isolate the problem in a separate project from the rest of my app so I can experiment with it, but I can't get it to reproduce, though it occurs 100% of the times on specific views in my app.
I know that's not nearly enough information to get an specific answer, but I just wanted to know if anyone ever heard of a navigation controller not popping the navigation items as expected, just so I could have some clue as to where to investigate next.
Here's an example of the code I use to push a view controller, it's pretty straightforward, I'm not trying to do anything special with it:
// pushing a view controller from a button press (set up with interface builder)
- (IBAction) tappedExtras
{
ExtrasViewController *controller = [[ExtrasViewController alloc] initWithNibName:#"ExtrasViewController" bundle:nil];
[self.navigationController pushViewController:controller animated:YES];
[controller release];
}
note: in that example I'm using a custom view controller class called ExtrasViewController, but the problem happened with any kind of view controller I tried.
And here's a bit of code used to pop the view controller explicitly, also triggered by a button press set up with interface builder:
- (IBAction) cancelChanges
{
userCancelled = YES;
[self.navigationController popViewControllerAnimated:YES];
}
this works perfectly (popping the view controller explicitly), but on the exact same view controller if instead of tapping the button set up with interface builder you tap the back button on the navigation bar, the navigation item is not popped correctly.
I got the same issue with navigation that subsist after poping the third level pushed view controller.
The issue only appear in landscape on iPad. No issue on the iPhone (3.1.3 & 4.0). Of course, it's ok on the simulator.
I have created an UITabView application. Each view selected from the bar is a seperate controller with own nib file. I switch between them succesfully.
In the first view I have two buttons (check out the screenshot). When clicking them I want to switch to another views which are the parts of the current view controller. I use:
[self presentModalViewController:anotherViewController animated:NO];
That switches the view, but hides the UITabBar. How to keep the bar on the screen after the switch?
P.S. Sorry for the blurred image. I am not allowed to share to much info.
Well I think you are misusing the modal view controller. For a problem like this I'll say you should put them in a view controller stack using UINavigationController. Instead of making each tab a UIViewController make it a UINavigationController, then you can push and pop view controllers on it, which still show the tab bar.
See http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UINavigationController_Class/Reference/Reference.html
use: tabBarController.selectedViewController = newViewController
edit: UINavigationController is not needed here.
I've come across this twice now.
Sometimes using the following line of code:
[self.navigationController presentModalViewController:aViewController animated:YES];
displays the view, but the navigation bar is then hidden.
I can write:
[self.navigationController setNavigationBarHidden:NO];
to my hearts content, everywhere I can think of with no effect.
Has anyone ran into this?
Am I doing something silly?
No, I ran into this as well. The problem is that when you present a modal view controller with a UIViewController based class, it does not extend the calling navigation controller's nav bar onto the modal. The modal view covers the entire screen. What I ended up doing to solve the problem was to create a UINavigationController and push the UIViewController based class onto it, and then do presentModalViewController to the navigation controller's instance.
like:
UIViewController *vc = [[UIViewController alloc] init];
UINavigationController *cntrol = [[UINavigationController alloc] initWithRootViewController:vc];
[self presentModalViewController:cntrol animated:YES];
[cntrol release];
That allowed me to have a nav bar at the top.
I am not sure if that will help in your particular case, the only other thing I would suggest is to replicate the behavior of the modal with a UIAnimation that stops 44px below the top of the phone. That would keep the original navigation bar visible.
#HeatMiser shows a great way to get around the "bug" surrounding the inability to display items on the nav bar. I'm not sure, however, if this is strictly a bug in Presentation, since modal operations ought to trump the underlying view's interface theme. Having the modal operation's theme mimic the underlying UI theme is fine, but wrapping the true modal view with a navigation view feels wrong to me (extra view object just to get a little more behavior).
Instead, the following worked for me and gives the same behavior as "New Message" does in the Mail program (on the iPhone).
In IB, place a UIToolBar at the top of the modal screen (mimicking the navigation bar) with "Cancel" and "Save" UIBarButtonItem's and a Flexible Space Bar Button Item in between to get the buttons to align left and right. Then, add a UILabel centered over the UIToolBar (The Font Helvetica, Bold, Size 18 appears to match the Navigation Bar Title). Connect the buttons to IBAction's on the modal's UIViewController, and you're done.
If there is a navigation controller active, then you should just use
[self.navigationController pushViewControllerAnimated:how];
to slide another view controller in, while giving yourself and the user into a consistent user interface complete with 'automatic' back button support.
Once a navigation controller is in use, presenting a modal view controller should only be done to enlarge the usable area on the screen. And then, you should really use a fancy animation to let the user know that you are stepping away from the "task" or "steps" that the navigation controller was embodying.
Maybe this is obvious, but once you're done with the modal view and want to dismiss it, you should do something like this in your modal vc:
[parentController dismissModalViewControllerAnimated:YES];
Where parentController is a reference to the vc from where you are presenting the modal view.