I have a UINavigationGroup with a root view controller called MainViewController. Inside this MainViewController I'm calling another UINavigationController as a modal as following:
- (IBAction)didTapButton:(id)sender {
UINavigationController * someViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"someNavigationController"];
[self.navigationController presentViewController:someViewController animated:YES completion:nil];
}
Inside this someNavigationController, the user is going through some process so the nav controller is being pushed with some UIViewControllers. After the user completes the process, in the last UIViewController called finalStepViewController, I'm closing the modal as follow:
[self dismissViewControllerAnimated:YES completion:nil];
The modal is indeed dismissed and the user is back to the initial MainViewController.
However, I'd like to push another UIViewController to MainViewController's NavigationController (for example: a view saying that the user completed the process successfully). Preferably before the modal is dismissed.
I have tried the following things:
1. Using presentingViewController
UIViewController * successViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"successViewController"];
[self.presentingViewController.navigationController successViewController animated:YES];
Result: no error, but nothing happening either.
2. Delegate/protocol
Imported finalStepViewController.h inside MainViewController.h and appended <finalStepViewControllerDelegate>
Inside MainViewController.m added a method called parentMethodThatChildCanCall to be called from finalStepViewController.m
Added the following to finalStepViewController.h:
#protocol finalStepViewControllerDelegate <NSObject>
-(void)parentMethodThatChildCanCall;
#end
#property (assign) id <finalStepViewControllerDelegate> delegate;
and #synthesize delegate; in the model
Set the delegate property to someViewController in the above mentioned didTapButton IBAction to self. This showed a notice error saying: Assigning to id<UINavigationControllerDelegate>' from incompatible type UIViewController *const __strong'
Finally called [self.delegate parentMethodThatChildCanCall] just before closing the modal.
Result: except for the notice error, no fail but nothing happens as parentMethodThatChildCanCall is not called.
Any idea what I'm doing wrong/what I should be doing? It's my second week doing Objective-C, and most of the time I don't know what I'm doing so any help/code would be appreciated!
Thanks.
You can achieve this a lot easier using NSNotificationCenter.
In your MainViewController's -viewDidLoad add the following code
typeof(self) __weak wself = self;
[[NSNotificationCenter defaultCenter] addObserverForName:#"successfullActionName"
object:nil
queue:[NSOperationQueue mainQueue]
usingBlock:^(NSNotification *note) {
SuccessViewController *viewController; // instantiate it properly
[wself.navigationController pushViewController:viewController animated:NO];
}];
Remove your controller from NSNotificationCenter upon dealloc
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
In FinalStepViewController on action that dismisses the view controller before dismiss post the notification
- (IBAction)buttonTapped:(id)sender {
[[NSNotificationCenter defaultCenter] postNotificationName:#"successfullActionName" object:nil];
[self dismissViewControllerAnimated:YES completion:nil];
}
This example is very crude and is not ideal, you should use constants for your notification names and in some cases store the observers returned by NSNotificationCenter to remove specific ones.
-- EDIT
I'd like to also mention that the method addObserverForName:object:queue:usingBlock: actually returns the observer as an id type object. You need to store a reference to it as an iVar in your class and remove it from the NSNotificationCenter when dealloc method is called otherwise that observer will never get deallocated.
Related
I have two view controllers one of them (ViewController) has a table called tableView.
I would like to refresh this table from my other view controller (pageView).
I have tried this in the pageView:
ViewController*refresh;
[refresh.tableView reloadData];
But this is not working.
The connecting segue between the two view controllers is a push segue
What should I do? Should I do it through a storyboard segue?
Option 1
#Class2
#property (nonatomic) BOOL shouldRefresh; // in .h file
- (void)viewWillAppear:(BOOL)animated // in .m file
{
[super viewWillAppear:animated];
if (_shouldRefresh) [self.tableView reloadData];
}
#Class1
// Add this in any method where you want it to refresh and push to view
ClassTwoController *viewController = [[ClassTwoController alloc] init];
[viewController setShouldRefresh:YES];
[self.navigationController pushViewController:viewController animated:YES];
*UPDATE:
Option 2
#Class 2
// Add this line in viewDidLoad in same class you want the tableView to refresh
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(refreshTableWithNotification:) name:#"RefreshTable" object:nil];
// Add this method just beneath viewDidLoad:
- (void)refreshTableWithNotification:(NSNotification *)notification
{
[self.tableView reloadData];
}
#Class1
// Call this when ever you want to refresh the tableView in Class2
[[NSNotificationCenter defaultCenter] postNotificationName:#"RefreshTable" object:nil userInfo:nil];
/* Add this line in viewDidLoad method in ViewController (by using this line you are adding notification observer to ViewController class) */
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(reloadTableview:) name:#"ReloadTableview" object:nil];
/* Add this method in ViewController class(this method call when you post notification in pageView) */
- (void)reloadTableview:(NSNotification *)notif
{
[tableView reloadData];
}
/* add this line when/where you want to refresh your (this line post notification which added in ViewController) */
[[NSNotificationCenter defaultCenter] postNotificationName:#"ReloadTableview" object:nil];
If second view controller is already loaded then you can use NSNotification in firstviewcontroller. This notification will invoke a method in second view controller. In this method write a code to reload a tableview.
If I understand correctly, you want to reload a table view that exists in the previous view controller of your navigation stack. If so, you can access it through the navigation controller's viewControllers property.
NSUInteger indexOfTableController = self.navigationController.viewControllers.count - 2;
ViewController *tableController = (ViewController*)[self.navigationController.viewControllers objectAtIndex:indexOfTableController];
[tableController.tableView reloadData];
Most often this happens because you're not initializing the reference to your second controller properly and it stays nil. Has to be something like this.
#implementation
{
ViewController *refresh;
}
- (void) openNewController
{
refresh = [[ViewController alloc] init];
[self.navigationController pushViewController:refresh animated:true];
}
- (void) refreshNewController
{
[refresh.tableView reloadData];
}
#end
Okay for sake of example lets call the previous ViewController VC1 and the current ViewController VC2.
So you do a push segue from VC1 to VC2. What you could do is: pass a reference of the TableView to VC2 during the segue. So you would create a public UITableView tblView variable in VC2 and then in VC1 implement the prepareForSegue method
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"Segue_Identifier_From_StoryBoard"])
{
// get your destination view controller
VC2 *vc2 = [segue destinationViewController];
vc2.tblView = TableView;
}
}
Then in VC2, you could just call [tblView reloadData];
Just make sure you nil the tblView reference once you are done with VC2.
In ViewController1 :
> Create property for UITableview with nonatomic and retain
> Now Create table Object.
In ViewController2.m:
ViewController1 *objV1 = [ViewController1 alloc]initWithNibName....];
[objV1.yourTableView reloadData];
You can check the adress of viewcontroller.tableview and refresh.tableView and i think they would be not the same;
you can make singleton for viewcontroller and then invoke for example
viewcontroller *vc = [viewcontroller sharedInstance];
[[vc tableview] reloadData];
In your pageView create a method
-(void) reloadVCController{
ViewController*vc=[[ViewController alloc]init]];
[vc.tableview reloadData;
}
And use it where you want to call it
[self reloadVCController];
ViewController*refresh;
[refresh.tableView reloadData];
By seeing the above code you are not assigning your ViewController instance to refresh. When executing reloadData() your refresh will be nil so obviously it won't react to any action.
ViewController*refresh = originalInstance; //assign your original instance here
[refresh.tableView reloadData];
this would work and the main point to be noted here is your refresh viewcontroller should be the top most instance in stack because any UI operation should happen in main thread.
Use NSnotification center add observer in that view controller and write method for reload table.
[self.tableView reloadData];
And from current view post notify that observer.
In case you have tried all the answers, make sure that before reloading the tableView, the dataSource is actually updated with new/additional/ content.
Reloaddata needs to execute within the parentviewcontroller because it invokes the tableview delegate methods to reload the table such as CellForRowAtIndexpath, and many more.
This means you need to define a public method in the parentviewcontroller that will contain the reloaddata command and call it from the child view controller.
public Method:
Parentviewcontroller.h
#interface
-(void) reloadTable:(id) sender;
parentviewcontroller.m
#implementation
- (void) reloadTable:(id) sender {
[self.tableview reloaddata];
return;
}
childviewcontroller.h
#import parentviewcontroller.h
#class parentviewController
#interface childviewcontroller :UIViewController (or UITableViewController)
#property (nonatomic, strong) parentViewController *parent;
childviewController.m
#implementation
#synthesize parent;
/* Note the parent instance is passed from the parent to the child view controller,
it is not allocated and initialised in the child controller - many ways to do this
depending on coding style */
/* after updating the data */
[parent reloadTable];
I think the problem is that you refresh controller view is not loaded. So, reloadTable message simply goes to nil. You can force a View Controller to load its view by calling view getter:
[viewController view];
So check if your tableView is nil and if it is, initialise it with described method.
As a make-up answer to emotality's:
If you want to skip the start-up animation, just simply set a bool property in your ClassTwoController to check if it's first time loading this view
ClassTwoController.h:
#property (nonatomic, assign) BOOL notFirstTimeRun;
ClassTwoController.m:
-(void)viewWillAppear:(BOOL)animated // in .m file
{
if(self.notFirstTimeRun) {
[self.tableView reloadData];
} else {
[self playStartUpAnime];
}
}
-(void)playStartUpAnimation // in .m file
{
//Place your codes for animation here
}
in your ClassOneController.m initialise it with the check bool:
ClassTwoController *viewController = [[ClassTwoController alloc] init];
viewController.notFirstTimeRun = YES;
If you have parent-child relationship you can add weak property to child viewcontroller like this
#property (nonatomic, weak) ParentViewController *parentController;
Then when you need to reload table you just call [parentController.tableView reloadData]
Other way would be using NSNotificationCenter. In controller you want to reload table you should subscribe to notification([[NSNotificationCenter defaultCenter] addObserver...]) and implement selector you supply to this method. In another controller you should post notification with that name.
Also you can just refresh on viewWillAppear if it suits your needs.
I am developing an iPad application using storyboard. In my application I have connected one modal view controller from first view controller using segue modal presentation.The modal view is dismiss by click one button appear in the modal view.How can i pass one dictionary from modal view controller to first view controller without using segue.
You can do passing value using Notification.
// Send Data
NSDictionary *aDictionary = [[NSDictionary alloc] initWithObjectsAndKeys:
anObject, #"objectName",
anotherObject, #"objectId",
nil] autorelease];
[[NSNotificationCenter defaultCenter] postNotificationName:#"AnythingAtAll" object:nil userInfo:aDictionary];
You can retrieve the dictionary from the inbound notification that you observe. Add the observer in advance of posting the notification.
//this might be in your init method or a viewDidLoad method of your FirstViewController
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(anyAction:) name:#"AnythingAtAll" object:nil];
enter code here
// for get data
-(void)anyAction:(NSNotification *)anote
{
NSDictionary *dict = [anote userInfo];
AnyClass *objectIWantToTransfer = [dict objectForKey:#"objectName"];
}
note that you should remove your object as an observer in the dealloc method.
[[NSNotificationCenter defaultCenter] removeObserver:self]
Using delegate its possible.
Go through this
Passing Data between View Controllers
its has easy and perfect answers.
You can create a Segue not bounded to a button by ctrl+drag from the first controller to the second one (don't forget to give this segue and identifier).
Next In the IBAction of the button (set via Interface Builder or via addTarget:self action:forControlEvents: ) you can call the [self performSegueWithIdentifier:#"YourSegueIdentifier" sender:button];
You can pass the data to the second controller, as usual, in - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
- (void)transitionFromViewController:(UIViewController *)fromViewController toViewController:(UIViewController *)toViewController duration:(NSTimeInterval)duration options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion {
SecondViewController *secVC = (SecondViewController*)toViewController;
secVC.property = self.property
}
Using Protocols is the best process for sending information to previous controller or any other controller
In your viewcontrooler where you presented write this in .h
#class yourclassName;
typedef void (^ yourclassName Callback) (NSDictionary*);
#protocol yourclassName Delegate
#required
- (void) yourclassNamedidReceiveData:(NSDictionary *)dataDict;
#end
in .m file
#synthesize delegate=_delegate;
#synthesize callbackBlock=_callbackBlock;
In some button action where you need to pass information back over there write this
[self yourclassNamedidReceiveData:yourDictHere]; // you can use any as per your requirement
Note: yourclassNamedidReceiveData method is declared in one class and now it is implemented in another class from where you will call this class
In your previous Controller(where you tried to present a class (suppose classA and classB ) first class is classA and presented class is classB.) in ClassA
- (void) yourclassNamedidReceiveData:(NSDictionary *)dataDict
{
}
Note* Do not forget to set delegate to classB EX:classBObject.delegate=self;
Hope this will help
I am new to iOS development and I am doing little project as a research.
I have an app where after I start it I am showing MainViewController, but if this is the first launch of this app I want to show Sub1ViewController (names are made up) using presentViewController method called in MainViewController.
After user puts in some data on Sub1ViewController I invoke dismissViewController method to hide it.
The hard part starts here - I have no idea how to capture the event when Sub1ViewController is dismissed and I can present Sub2ViewController also using presentViewController invoked from MainViewController. All the time I am getting messages that I am trying to present view when another present or dismiss is in progress.
PS: I am using Xamarin, but I also understand objective-c.
hi you can try out this
[self dismissViewControllerAnimated:YES completion:^{
//code to be executed with the dismissal is completed
// for example, presenting a vc or performing a segue
}];
you can write code after completion of dismiss one view controller
or
You can achieve this by present view after some delay in dismiss method
-(void)onDismisViewController{
[self performSelector:#selector(presentSecoundViecontoller) withObject:self afterDelay:1];
}
-(void)presentSecoundViecontoller
{
SecoundViewController *secoundVC = [[SecoundViewController alloc] initWithNibName:#"secoundVC" bundle:nil];
[self.navigationController presentViewController:secoundVC animated:YES completion:NULL];
}
EDIT
Try this i Try and it work
crate one delegate Method in subviewcontroller1 and set delegate in mainviewcontroller and implement method in mainvie and present subviewcontroller2 in this delegate method its work
try this if not let me know will post code.
Delegate Creation on subviewcontroller1.h file
#protocol st1Protocol <NSObject>
- (void)presentViewController;
#end
#interface SubViewController1 : UIViewController
#property (nonatomic,assign) id <st1Protocol> delegate;
- (IBAction)dissmiss:(id)sender;
SubViewcontroller1.m file
i put dismiss view on button click of subviewcontroller1 you do this in you dismiss method
- (IBAction)dissmiss:(id)sender {
[self dismissViewControllerAnimated:YES completion:^{
//code to be executed with the dismissal is completed
// for example, presenting a vc or performing a segue
[self.delegate presentViewController];
}];
}
now implementation of this delegate method in main view controller.
implement delegate method in .h file
#interface StViewController : UIViewController<st1Protocol>
set delegate in mainviewcontroller.m file view didload
- (void)viewDidLoad
{
[super viewDidLoad];
subViewcontroller1 *st1=[[subViewcontroller1 alloc]initWithNibName:#"subViewcontroller1" bundle:nil];
st1.delegate=self;
[self presentViewController:st1 animated:YES completion:nil];
// Do any additional setup after loading the view from its nib.
}
delegate method implementation in main view controller
-(void)presentViewController{
SubmViewcontroller2 *st2=[[SubmViewcontroller2 alloc]initWithNibName:#"St2ViewController" bundle:nil];
[self presentViewController:st2 animated:YES completion:nil];
}
hope this may help you happy coding.
Hello I do not have very much programming experience and I'm trying to call a method when the user leaves the app. I know that I am going to use the app delegate methods applicationDidEnterBackground, but how do I make that call a method that is in my ViewController class?
Thanks so much for any help!
ViewController.h:
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController <ADBannerViewDelegate>
{
//Images and buttons
}
-(void)stop;
#end
You can use a notification here. Create a listener for this notification in the viewDidLoad of the viewController and assign the function to it.
eg:
in yourView controller add the following in the viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(notificationEnabled) name:UIApplicationDidEnterBackgroundNotification object:nil];
You can either
observe UIApplicationDidEnterBackgroundNotification inside your ViewController, or
invoke your ViewController method inside appDelegates applicationdidEnterBackground: method. App delegate should have a pointer that points to the rootViewController, ie: your ViewController
goodluck!
edit:
...
-(void)applicationDidEnterBackground:(UIApplication *)application {
UIViewController *uvc= [UIApplication sharedApplication].keyWindow.rootViewController;
ViewController *myvc = (ViewController*) uvc;
[myvc stop];
}
.
When you close or leave your App, AppDelegate methods automatically called, you not need to call them in some specific ViewController.
For doing something when your App is in background you can implement your logic in AppDelegate's applicationDidEnterBackground: method.
Or if your App is not running(means closed) AppDelegate Method didFinishLaunchingWithOptions: is called.
I didn't get the purpose of calling the method inside UIViewController. Eventhough you can create an instance of your viewcontroller inside applicationDidEnterBackground and call the corresponding method in viewcontroller using that object
you can do this by creating an instance of that View and then calling specific method of that view
otherwise if your view is opened then you can find it by follwing code & then call specific method by using that obj as follow in your applicationDidEnterBackground
NSArray *AllViewControllers = [self.navigationController viewControllers];
for (UIViewController *aViewController in AllViewControllers) {
//NSLog(#" >> Nav Stack %#", [aViewController class]);
if ([aViewController isKindOfClass:[YourViewController class]]) {
[(YourViewController *)aViewController yourMethodToCall];
break;
}
}
I have two view controllers, FirstViewController and FourthViewController. FirstViewController is my initial view controller. I present FourthViewController with
UIViewController *fourthController = [self.storyboard instantiateViewControllerWithID:#"Fourth"];
[self presentViewController:fourthController animated:YES completion:nil];
Then, in FourthViewController's .m I'd like to change the text of a UILabel in FirstViewController. So I use
UIViewController *firstController = [self.storyboard instantiateViewControllerWithID:#"First"];
firstController.mainLab.text = [NSMutableString stringWithFormat:#"New Text"];
However, after I use
[self dismissViewControllerAnimated:YES completion:nil];
I find that my mainLab's text has not updated. Does anyone know why?
When you are calling this line from FourthViewController.m you are actually creating a new instance of FirstViewController, rather than using the already created one.
UIViewController *firstController = [self.storyboard
instantiateViewControllerWithID:#"First"];
You can tackle this in two ways.
1) Using notification
post a notification from FourthViewController when label text need to be changed.
[[NSNotificationCenter defaultCenter] postNotificationName:#"updateLabel"
object:self];
In your FirstViewController viewDidLoad methodcreate an observer that waits for this notification to get fired.
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(updateLabelCalled:)
name:#"updateLabel"
object:nil];
Implement updateLabelCalled: and update label.
- (void) updateLabelCalled:(NSNotification *) notification
{
if ([[notification name] isEqualToString:#"updateLabel"]){
//write code to update label
}
}
2) Implementing delegate
It is already explained here in stackoverflow. The basic idea is you create a FourthViewController delegate, and create a delegate method to updateLabel. FirstViewController should implement this method.
If you want to update the label on first screen and nothing else then go for notifications. It's better rather you write the delegate. Because you want to update only label text thats it.