I have a UIViewController called ShowListViewController that uses a Modal View Controller to push another view onto the stack:
AddShowViewController *addShowViewController = [[AddShowViewController alloc] init];
[addShowViewController setModalTransitionStyle:UIModalTransitionStyleCoverVertical];
[self presentModalViewController:addShowViewController animated:YES];
I would then like to call my method populateTableData of the ShowListViewController class when the addShowViewController disappears.
I would think that the answer found here would work, but it doesn't. My method populateTableData is not detected as an optional method to use.
Essentially my questions is: How do I detect when a Modal View Controller disappears so as to call a method within the class that pushed it on the stack?
This may not be a best solution, but can do what you want at this time.
In your showlistcontroller add an instance variable like
BOOL pushedView;
#implementation ShowListViewController
and before you do the modal presentation set its values as YES like
pushedView = YES;
[self.navigationController presentModalViewController:popView animated:YES];
in the viewWillAppear of ShowListViewController you can detect whether it is appearing because pop getting dismissed or not like
if (pushedView) {
NSLog(#"Do things you would like to on pop dismissal");
pushedView = NO;
}
I think you would like something like this.
You make a delegate inside ur modalVC like this:
#protocol ModalViewDelegate <NSObject>
- (void)didDismissModalView;
#end
and implement it in your MainVC like this:
#interface MainViewController : UIViewController <ModalViewDelegate>
{
Then u will make a delegate property in your modalVC like this:
#interface ModalShizzle : UIViewController
{
id<ModalViewDelegate> dismissDelegate;
}
You set the dismissDelegate of your ModalVC to your MainVC and then you make the delegate method. Before you dismiss it however you will call the ModalVC to do one last thing. (which is populate your table). You will call for the data inside your MainVC and then do whatever you feel like it, just before you dismissed your modalVC.
-(void)didDismissModalView
{
//call ModalVC data here...
//then do something with that data. set it to a property inside this MainVC or call a method with it.
//method/data from modalVC is called here and now u can safely dismiss modalVC
[self dismissModalViewControllerAnimated:YES];
}
Hope it helps ;)
OK so it appears that in Apple's template for Utility App's they ignore what the docs for [UIViewController][1] say and actually go out of their way to call dismissModalViewControllerAnimated: from the UIViewController that pushed the modal view onto screen.
The basic idea in your case will be
Define a protocol for AddShowViewControllerDelegate
Make ShowListViewController implement this protocol
Call a method on the delegate to ask it to dimiss the modal view controller
For a full example just create a new project with Utility template and look at the source for FlipsideViewController and MainViewController
Here is an example adapted for your needs:
AddShowViewController.h
#class AddShowViewController;
#protocol AddShowViewControllerDelegate
- (void)addShowViewControllerDidFinish:(AddShowViewController *)controller;
#end
#interface AddShowViewController : UIViewController
#property (nonatomic, assign) id <AddShowViewControllerDelegate> delegate;
- (IBAction)done:(id)sender;
#end
AddShowViewController.m
- (IBAction)done:(id)sender
{
[self.delegate addShowViewControllerDidFinish:self];
}
ShowListViewController.h
#interface ShowListViewController : UIViewController <AddShowViewControllerDelegate>
{
...
}
ShowListViewController.m
- (void)addShowViewControllerDidFinish:(AddShowViewController *)controller
{
[self dismissModalViewControllerAnimated:YES];
[self populateTableData];
}
Related
How would I go about changing the a UILabel property in another view controller?
I have #import "SecondViewController.h" imported in the FirstViewController.m file and then
I have the following in a method in FirstViewController
-(IBAction) someAction {
SecondViewController *objV1 = [[SecondViewController alloc]init];
objV1.secondViewControllerLabel.alpha = 0.2;
NSLog(#"someAction");
}
when someAction is called nothing happens to the UILabel in the SecondViewController.
also, in this example both first and second view controllers are in another view controller called MainViewController. So, they are both onscreen at the same time.
thanks for any help.
From what you tell us, it would seem that you need to set the "embeded view controllers" as childs of the parent View Controller.
[mainViewController addChildViewController:childViewController];
[childViewController.view setFrame:self.view.bounds];
[self.childContainerView addSubview:childViewController.view];
[childViewController didMoveToParentViewController:self];
This is very powerful, because you can forward IBActions from the mainViewController to their child...
[mainViewController childViewControllers]
Returns an array of them, and also take a look at
– shouldAutomaticallyForwardRotationMethods
– shouldAutomaticallyForwardAppearanceMethods
So your child get automatically informed about the rotations of their parent.
To answer your question, you could do something like:
// In Parent View Controller
- (IBAction) anAction:(id) sender
{
for (CustomChildController *child in self.viewControllers) {
[child handleSomeAction];
}
}
Check out what the docs say for more details.
#Goles answer will work, but if you specifically want to trigger the change from FirstViewController.m you need to pass in a reference to SecondViewController somehow.
So you could do it with a custom init that takes a reference to your second viewcontroller as a parameter, or create a property on your FirstViewController that you can set from outside, which would be something like this:
FirstController.h:
#interface
..
#property (strong, nonatomic) UIViewController *second;
...
#end
FirstController.m:
#implementation
#synthesize second
In your parent ViewController you would create both the child view controllers, then:
ViewController1.second = ViewController2;
Then your action method would become:
-(IBAction) someAction {
self second.secondViewControllerLabel.alpha = 0.2;
NSLog(#"someAction");
}
Since in the secondViewController, secondViewControllerLabel has not been created yet, 'objV1.secondViewControllerLabel.alpha' will have no effect. Ideally, you should create a NSNumber property called labelAlpha in the secondViewController, set that property in the firstViewController, and then in the viewDidLoad of the second controller, add this line ::
self.secondViewControllerLabel.alpha = self.labelAlpha;
This will work for you.
I have 2 ViewControllers, in 1st - TableView and in 2nd - button with label on it. When I click on the button in 2nd ViewController I need to go back on TableView and set in
cell.detailTextLabel.text
text from label on the button.
For go back to first view I use:
[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:1] animated:YES];
but how I can set label from second view to:
cell.detailTextLabel.text
in first view?????
I would define a protocol & delegate in the second view controller
#protocol SecondViewController;
#interface SecondViewController : UIViewController
#property (nonatomic, assign) id<SecondViewController> delegate;
#end
#protocol SecondViewController <NSObject>
- (void)secondViewController:(SecondViewController *)controller didTappedOnButton:(UIButton *)button;
#end
then when the button is tapped call the delegate:
- (IBAction)buttonTapped:(UIButton *)sender
{
// do somthing..
// then tell the delegate about the button tapped
[self.delegate secondViewController:self didTappedOnButton:sender];
}
In your first view controller implement the protocol
#interface FirstViewController : UIViewController <SecondViewControllerDelegate>
when you push the second view controller, set the first as the second delegate:
- (void)someMethodThatPushTheSecondViewController
{
SecondViewController *svc = [[SecondViewController alloc] init];
[self.navigationController pushViewController:svc animated:YES];
svc.delegate = self;
}
And implement the delegate method to get notified when the button tapped
- (void)secondViewController:(SecondViewController *)controller didTappedOnButton:(UIButton *)button
{
// do somthing after button tapped
// you can get the button title from button.titleLabel.text
}
To access a parent class method or property you gotta implement a protocol, and use it's delegates. You can access child class methods/properties using it's class object that you create in the current (parent) class. But how you want to access a parent class entity from a child class? YES, implementing protocols.
Or the newbie way: after tapping your button, save the needed value into NSUserDefaults. Then, when you go to your parent class (viewController 1), ion viewWillAppear, check that saved value, and if it's not nil, display it.
[self.navigationController popViewControllerAnimated:YES];
I have a View-based app. The first view that is loaded has a button which loads another view using this code:
AddPost *addView = [[AddPost alloc] initWithNibName:#"AddPost" bundle:nil];
addView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:addView animated:YES];
What I want to do is provide a button on the view (AddPost) that will let me close it and go back to the original view. How can I do this?
It seems a little strange, but you can actually have addView call:
[self dismissModalViewControllerAnimated:YES];
From the docs:
"The parent view controller is responsible for dismissing the modal view controller it presented using the presentModalViewController:animated: method. If you call this method on the modal view controller itself, however, the modal view controller automatically forwards the message to its parent view controller."
The answer Conrad gave will work perfectly well. In the name of slightly better encapsulation you could put a delegate protocol on addView and have your first view implement this.
So in the header file for your addView controller:
#protocol addViewDelegate <NSObject>
- (void)addViewRequestDismissal;
#end
You will also need an external properly on the addView controller:
#property (assign) id<addViewDelegate> delegate;
Then make your first view controller implement this, so in it's .h file you should have
#interface firstView : NSObject <addViewDelegate> {
}
When you instantiate your addView remember to set the delegate:
addView.delegate = self;
In the addView controller when your button is pressed call back:
- (void)buttonPressed {
[self.delegate addViewRequestDismissal];
}
Finally in your first view remember to implement this method
- (void)addViewRequestDismissal {
[self dismissModalViewControllerAnimated:YES];
}
Hope all goes well with this. Post back if you have any further problems :)
I have a mainViewController. I call [self pushModalViewController:someViewController] which makes someViewController the active view.
Now I want to call a function in mainViewController as someViewController disappears with [self dismissModalViewController].
viewDidAppear does not get called probably because the view was already there, just beneath the modal view. How does one go about calling a function in the mainViewController once the modalView dismisses itself?
Thanks a lot!
This answer was rewritten/expanded to explain the 3 most important approaches (#galambalazs)
1. Blocks
The simplest approach is using a callback block. This is good if you only have one listener (the parent view controller) interested in the dismissal. You may even pass some data with the event.
In MainViewController.m
SecondViewController* svc = [[SecondViewController alloc] init];
svc.didDismiss = ^(NSString *data) {
// this method gets called in MainVC when your SecondVC is dismissed
NSLog(#"Dismissed SecondViewController");
};
[self presentViewController:svc animated:YES completion:nil];
In SecondViewController.h
#interface MainViewController : UIViewController
#property (nonatomic, copy) void (^didDismiss)(NSString *data);
// ... other properties
#end
In SecondViewController.m
- (IBAction)close:(id)sender
{
[self dismissViewControllerAnimated:YES completion:nil];
if (self.didDismiss)
self.didDismiss(#"some extra data");
}
2. Delegation
Delegation is the recommended pattern by Apple:
Dismissing a Presented View Controller
If the presented view controller must return data to the presenting view controller, use the delegation design pattern to facilitate the transfer. Delegation makes it easier to reuse view controllers in different parts of your app. With delegation, the presented view controller stores a reference to a delegate object that implements methods from a formal protocol. As it gathers results, the presented view controller calls those methods on its delegate. In a typical implementation, the presenting view controller makes itself the delegate of its presented view controller.
MainViewController
In MainViewController.h
#interface MainViewController : UIViewController <SecondViewControllerDelegate>
- (void)didDismissViewController:(UIViewController*)vc;
// ... properties
#end
Somewhere in MainViewController.m (presenting)
SecondViewController* svc = [[SecondViewController alloc] init];
svc.delegate = self;
[self presentViewController:svc animated:YES completion:nil];
Somewhere else in MainViewController.m (being told about the dismissal)
- (void)didDismissViewController:(UIViewController*)vc
{
// this method gets called in MainVC when your SecondVC is dismissed
NSLog(#"Dismissed SecondViewController");
}
SecondViewController
In SecondViewController.h
#protocol SecondViewControllerDelegate <NSObject>
- (void)didDismissViewController:(UIViewController*)vc;
#end
#interface SecondViewController : UIViewController
#property (nonatomic, weak) id<SecondViewControllerDelegate> delegate;
// ... other properties
#end
Somewhere in SecondViewController.m
[self.delegate myActionFromViewController:self];
[self dismissViewControllerAnimated:YES completion:nil];
(note: the protocol with didDismissViewController: method could be reused throughout your app)
3. Notifications
Another solution is sending an NSNotification. This is a valid approach as well, it might be easier than delegation in case you only want to notify about the dismissal without passing much data. But it's main use case is when you want multiple listeners for the dismissal event (other than just the parent view controller).
But make sure to always remove yourself from NSNotificationCentre after you are done! Otherwise you risk of crashing by being called for notifications even after you are deallocated. [editor's note]
In MainViewController.m
- (IBAction)showSecondViewController:(id)sender
{
SecondViewController *secondVC = [[SecondViewController alloc] init];
[self presentViewController:secondVC animated:YES completion:nil];
// Set self to listen for the message "SecondViewControllerDismissed"
// and run a method when this message is detected
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(didDismissSecondViewController)
name:#"SecondViewControllerDismissed"
object:nil];
}
- (void)dealloc
{
// simply unsubscribe from *all* notifications upon being deallocated
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
- (void)didDismissSecondViewController
{
// this method gets called in MainVC when your SecondVC is dismissed
NSLog(#"Dismissed SecondViewController");
}
In SecondViewController.m
- (IBAction)close:(id)sender
{
[self dismissViewControllerAnimated:YES completion:nil];
// This sends a message through the NSNotificationCenter
// to any listeners for "SecondViewControllerDismissed"
[[NSNotificationCenter defaultCenter]
postNotificationName:#"SecondViewControllerDismissed"
object:nil userInfo:nil];
}
Hope this helps!
Using exit (unwind) segue
When you're using storyboards and segues you can use a very handy approach with minimal code to dismiss a modal view controller and inform the underlying view controller that the modal view controller has been closed.
Using exit (unwind) segues you gain 3 advantages:
you don't need to write any code to dismiss the modal view controller and
you can have iOS call a callback method inside the underlying view controller that has presented the model view controller.
you use the very same semantics that you already know from implementing prepareForSegue:
Implement it with only 2 steps
Create an action method in the Parent view controller that presents another (modal) view controller:
Swift
#IBAction func unwindFromSegue(segue: UIStoryboardSegue) {
print("Unwind from segue", segue.identifier)
}
Objective-C
- (IBAction)unwindFromSegue:(UIStoryboardSegue *)segue {
NSLog(#"Unwind from segue %s", segue.identifier);
}
In the storyboard, On child view controller right click the exit segue (aka unwind segue, it's the last of the icons at the top of your view controller), drag & drop unwindFromSegue: to your button and select action.
You're done! Now the modal view controller closes when you click the dismiss button and unwindFromSegue: informs your underlying view controller(Parent) that the modal view controller(Child) has closed.
Here's a callback solution which takes less modifications to your modal and parent:
In the Model's .h add:
#property (nonatomic, copy) void (^dismissed)();
In the Model's .m put this in the completion when you dismiss the modal:
[self dismissViewControllerAnimated:YES completion:^{
if(self.dismissed)
self.dismissed();
}];
In the parent view controller when you instantiate your modal set the dismissed callback:
Modal = //Init your modal
[Modal setDismissed:^{
//do stuff you wanted when it's dimissed
}];
[self presentViewController:Modal animated:YES completion:nil];
Is there a way to call code when a modal view is finished dismissing?
EDIT:
I'm sorry, I didn't clarify earlier. I'm trying to dismiss a UIImagePickerController and then show a MFMailComposeViewController and attach the image data to the email. When I try to call
[self presentModalViewController: mailController]
right after
[self dismissModalViewController];
I get errors and such.
You use a delegate pattern for the modal view to inform whoever presented it when it's finished.
MyModalViewController.h:
#protocol MyModalViewControllerDelegate;
#interface MyModalViewController : UIViewController
{
id<MyModalViewControllerDelegate> delegate;
}
#property (nonatomic, assign) id<MyModalViewControllerDelegate> delegate;
#end
#protocol MyModalViewControllerDelegate
- (void)myModalViewControllerFinished:(MyModalViewController*)myModalViewController;
#end
MyModalViewController.m:
#synthesize delegate;
// Call this method when the modal view is finished
- (void)dismissSelf
{
[delegate myModalViewControllerFinished:self];
}
ParentViewController.h:
#import "MyModalViewController.h"
#interface ParentViewController : UIViewController <MyModalViewControllerDelegate>
{
}
ParentViewController.m:
- (void)presentMyModalViewController
{
MyModalViewController* myModalViewController = [[MyModalViewController alloc] initWithNibName:#"MyModalView" bundle:nil];
myModalViewController.delegate = self;
[self presentModalViewController:myModalViewController animated:YES];
[myModalViewController release];
}
- (void)myModalViewControllerFinished:(MyModalViewController*)myModalViewController
{
[self dismissModalViewControllerAnimated:YES];
}
EDIT:
I haven't used UIImagePickerController, but looking at the docs, it looks like you already have most of the code done for you, as there is an existing UIImagePickerControllerDelegate class that has three different "dismissal" delegate callbacks (although one is deprecated). So you should make your ParentViewController class (whatever that is) implement the UIImagePickerControllerDelegate pattern and then implement those methods. While each method will do something different (since you have to handle when the user actually selects an image, or if they cancel), they each will do the same thing at the end: call dismissModalViewControllerAnimated: to dismiss the picker.
You have to dismiss the modalViewController somehow right? Either a UIButton, or by code:
- (void)dismissModalViewControllerAnimated:(BOOL)animated
In the IBAction (e.g. delegate) for the UIButton or in the method above, call whatever code you want.
I don't think there is a specific notification yet can subscribe to, to know when dismiss animation is done,...BUT. You can implement viewDidAppear: in the view controller that presented the modal view. This is what I do, when I use the (to UIImagePickerController quite similar) ABPeoplePickerNavigationController.
In the callback from people picker, I remember the person tapped in the picker on an instance variable, like this:
- (void)callbackFromModalView:(id)dataFromModalView {
// remember dataFromModalView as I need it when dismissed
self.dataFromModalView = dataFromModalView;
// now initiate dismissal
[self dismissModalViewControllerAnimated:YES];
}
then, in your view controller, implement this:
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
if (self.dataFromModalView) {
//...present now view here
// don't forget to reset this one
self.dataFromModalView = nil;
}
}
in effect, you are using the combination of viewWillAppear: and the dataFromModalView property as the "notification about modal view dismissed".