I have a table view that pushes to a detail view controller. From the detail view controller, when I press the 'back' button, I'd like an integer value to change. How do I edit the navigation bar back button's action programatically. The back button is automatically placed in my app because I'm using a table view so I didn't actually create the button, so I don't know how to affect it's method.
To be clear, I still want the back button to go back to the original view, but simultaneously change an integer's value. Thanks!
Thanks PengOne to point me to this direction.
Add the UINavigationBarDelegate in the header file and use this in the .m file:
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item
{
//insert your back button handling logic here
// let the pop happen
return YES;
}
I've figured out an easy fix to this. I simply unchecked 'Shows Navigation Bar' in the Interface Builder for the UINavigationController that the Table View was contained in. Then I used a UINavigationBar to replicate the look (but be able to add and delete buttons as I pleased).
After that I just created IBAction's that I connected to the buttons and could control an integer value from there.
(P.S. The only problem with this is that there is no 'Back' button left pointing arrow shape in the XCode interface builder as many of you know. There are solutions around this that are pretty easily found if you search).
If you're using a UINavigationController, then UINavigationBarDelegate is the delegate class and it implements -navigationBar:shouldPopItem. You can put the action you want to trigger in that method, e.g. incrementing or decrementing a counter.
You could try implementing viewDidDisappear, which should be called as the detail view controller's view goes out of view.
Related
I'm having trouble piecing this all together. I have a view controller that opens up another (pushes it on to the navigation stack). On that presented view controller, the user enters a value in a text view. When the user pushes the back button in the navigation, I want to be able to pass the value that they entered in the text view back to the presenting controller.
I've looked for a way to use unwind segue with the back button but haven't found anything. When I create my back button (programmatically) I use initWithTitle:style:target:action but I'm not sure how in implementing the action method that I'll be able to access the value set in the presented controller. Might have to use a delegate to link the two, but not sure of the exact integration point for this scenario.
I feel like I'm so close here and a little help would get me there. Thanks!
The two most common models to use for this interaction are for the child view controller to have either a delegate or a completion block. Either would be set in the prepareForSegue method. My personal preference is the completion block method just because it keeps code contained, but ymmv.
There are also multiple models for detecting when your child view controller is dismissed and you need to invoke the delegate and/or completion:
Use a custom back button. Not a fan of this as it can be an issue to create a back button that really looks and acts like the Apple original, especially if supporting iOS 6 and iOS 7.
Hook viewDidDisappear and see if you're still in the navigation controller's viewControllers array. This is better as the back button works right, but it still feels kind of hokey.
Use the UINavigationBarDelegate method navigationBar:shouldPopItem: This is attractive, especially if you have other validation that needs to happen like checking for saved/unsaved values. To implement this you'll have to subclass UINavigationController and forward the method to your child view controller.
EDIT: Details on Option 2:
-(void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
if(![self.navigationController.viewControllers containsObject:self])
{
// We're not still in the navigation stack so we must've been
// popped. If we were pushed, viewDidDisappear would be called
// but viewControllers containsObject:self would be true
}
}
EDIT: Clarified Option 3: in your navigation controller subclass
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item
{
UIViewController* top = self.topViewController;
if([top respondsToSelector:#selector(navigationBar:shouldPopItem:)])
return [(id)top navigationBar:navigationBar shouldPopItem:item];
return [super navigationBar:navigationBar shouldPopItem:item];
}
Then you can implement navigationBar:shouldPopItem: in the classes that need the functionality.
the back button does not actually comes up with any event associated with itself so that you can pass the values between the previous and to be Popped ViewController.
You would have to implement Delegate pattern to pass values. In this case as you cant catch when backButton is pressed, you need to use custom leftBarButtonItem or use a image with < in itself.
I am trying to segue back to a home screen and pop everything from the stack (of views?)
I am using UINavigationController:
[self.navigationController popToRootViewControllerAnimated:YES];
Where shall I call this method? I have tried in -(void) prepareForSegue which does not work.
Basically I want to make sure when I go back to home screen there is no back button on the left of the title.
Home screen here refers to the welcome screen of my App.
I am not sure which part of my code shall be posted. Please comment if you need to see my code.
Thank you in advance.
Assuming you're using a Storyboard, and a UIButton declared over there is the one that triggers that action you wanna perform, you should declare an IBAction: -(IBAction)buttonPressed:(id)sender; in the .h and implement it in the .m. Inside that method should appear that [self.navigationController popToRootViewControllerAnimated:YES]; code. Also remember to attach that action to that UIButton when touch up inside in the storyboard.
Hope it helped!
I think your confusion is around the concepts of what a segue is and how it relates to the navigation controller stack. The stack is exactly the same as the basic data structure stack (http://en.m.wikipedia.org/wiki/Stack_(abstract_data_type)) in that it's a last-in-first-out store. When you segue, you're normally adding to that stack, e.g. Pushing a new VC onto the stack. A back button in most cases would not be doing that. It would be popping, or removing from the stack. Which is why you probably wouldn't call pop methods from the prepareForSegue method. Instead try calling it at some other point, like when they tap the back button, or after some action has taken place.
I'm attempting to create a custom tab bar controller with the following options:
Feed
Map
New
Camera
Search
The feed, map, camera, and search will each pull up their individual VC's, while new is supposed to be more of a functionality button. When the new tab item is pressed, the map view should be displayed, and the map should begin recording the user's location. I'm trying to use a UITabBarController to manage these views, but I cannot seem to figure out how to implement the functionality that I would like with the "New" tab. It seems as if I would need to implement a separate view controller for the "New" record and stop functionality but that doesn't seem right.
The functionality of record/stop should be similar to snapchat's big red button that takes a picture when you press it.
While I agree with Scott's comment that this is a bad UX, if you technically wanted to do it, you could subclass UITabBarController and in viewDidLoad you could add a UIButton subview to the the tab bar controller's tabBar:
[self.tabBar addSubview:yourCustomButton];
Thus, this button could have it's own action and selector to do whatever you want with.
Take a look at idevrecipes for an example.
I think you have to implement the container view controller yourself. I think you can't do that with UITabBarController.
I was going to dig up the idevrecipes example that shawnwall pointed out, but there's another possibly answer, assuming you want the New button to match the standard UITabBarButton appearance. I agree it may not be the best UI, but it's workable.
For starters, you would create a dummy view controller for the New item. I'm not saying you should duplicate the Maps controller or anything, I'm just saying create an empty view controller and stash to it (or it's location) in a property. Assuming you're creating your tab bar in application:didFinishLaunchingWithOptions:, it'd look something like this.
self.newViewController = [[UIViewController alloc] init];
self.newViewController.title = NSLocalizedString(#"New", nil);
self.newViewController.image = [UIImage imageNamed:"new.png"];
Drop that view controller at the appropriate location in the tab bar controller's viewControllers property.
Save a reference to the Maps controller the same way you saved one for the dummy New controller.
If you haven't already done do, set the delegate of your tabBarController to your app delegate. You may need to declare that your app delegate conforms to UITabBarControllerDelegate.
UITabBarDelegate gives you a few hooks for tracking changes to the tab bar. tabBarController:shouldSelectViewController: looks to be the appropriate place for us to hook in for your desired behavior.
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
if ([viewController isEqual:self.newViewController]) {
self.tabBarController.selectedViewController = self.mapViewController;
// Whatever logic you need to start the recording
return NO;
}
return YES;
}
The look of the user interaction's a little odd - the user tabs the middle item (New), but the item to the left (Map) gets selected. If you want the "tab bar triggers behavior" action, I'd go the idevrecipes route and make the button visually distinct. If you're married to the tab bar item look, though, I believe this is how you'd accomplish it.
I am creating an app using iOS 5 SDK. I managed to push views using the Storyboard's Segues, but I cannot find the proper way to pop the current view and go back to the previous one.
I am not using any navigationController (the app doesn't have any top or bottom bars).
I don't think using modal or push segue the other way would be the solution as it instantiates a new controller.
Do I have to use a custom Segue with the opposite animation and deletion of the view at the end ? Or is there a better way ?
Storyboards in iOS 5 don't provide a "no-code" way to return from a segue -- that's something you'll need to implement yourself.
If you use "push" segues (which require a navigation controller), use the navigation controller's popViewControllerAnimated: method to undo the last push segue. (Or other methods to undo more; see the UINavigationController documentation.)
If you use "modal" segues, call dismissViewControllerAnimated:completion: on the view controller which presented the current view controller (which you can get from its presentingViewController property).
Update: In iOS 6 and later there's unwind segues for going "back" in a storyboard. It's still not a no-code solution -- and it shouldn't be, because you need to be able to do things like differentiating between "Done" and "Cancel" exits from a modal view controller. But it does let you put more of the semantic flow of your app into the storyboard. Apple has a tech note that describes them in detail, and they're also covered in the video from WWDC 2012 Session 407.
You could try calling [self dismissViewControllerAnimated:YES completion:nil]; from the controller you want to dismiss (whether the controller has been pushed, or shown modally).
Here is the related documentation : UIViewController Class Reference
The presenting view controller is responsible for dismissing the view controller it presented. If you call this method on the presented view controller itself, it automatically forwards the message to the presenting view controller.
Just to clarify.
In the class that was pushed. Simply wire up the following and the controller and view will be popped off.
[self.navigationController popViewControllerAnimated:YES];
Create Segue type "Custom" on your stroyboard. This can be from a button.
Create a new UIStoryboardSegue class named "popSegue"
In the popSegue.m file add the following;
-(void)perform{
UIViewController *sourceViewContreoller = [self sourceViewController];
[sourceViewContreoller.navigationController popViewControllerAnimated:YES];
}
-In the storyboard editor.
-Select the segue and change the Segue Class to "popSegue"
-Set the Identifier to "popSegue"
Done!
You can use the same "popSegue" class throughout your project.
Hope this helps
I'm using Xcode 5 also and here's how it's done. First, in the view code file that pushed the other, create an IBAction method in the .h file such as this:
- (IBAction)exitToHere:(UIStoryboardPopoverSegue *)segue sender:(id)sender;
Then in the .m file add this:
- (IBAction)exitToHere:(UIStoryboardPopoverSegue *)segue sender:(id)sender {
}
You can add any cleanup code you want executed in this method. Next go to your storyboard and select the pushed view. I assume you've got some kind of button on the view that the user taps to signal he's finished. Click on that button, hold down the key and drag to the the green box below the view which is the Exit. Release the mouse button but continue to hold the key. A popup will appear and your method will show in the list. Select that method. Now when the user clicks on the button, the view will pop and you'll be returned to the starting method.
I'm trying to add some finer control to the Storyboard controller and I hit a blockage with the back button.
I have a basic Storyboard with push transition. I want to be able to catch when the user presses on the back button (the one generated automatically) and decid if I want the view to go back or not.
The scenario is to show a message to the user asking if he wants to go back warning him that he is going to lose his work if he does,
Sounds simple, yet I can't find how to do it.
Any ideas
You don't get any sort of message by default when the back button is pressed. If you want to provide this sort of functionality, you have two options:
1) Provide a custom back button and set it as the leftNavigationItem of your UIViewController's navigation bar
2) Subclass UINavigationController and override a method such as popToRootViewController:animated:
Try using UIAlertView Delegate.
In your buttonPressed Action, provide an alert view with message with two buttons YES and NO.
define button at index action for YES and NO -ie- YES: dismiss current view and NO: remain on current view.
Search Apple Docs on alert view delegate