I am quite new to IOS, and I was working with delegates to call a method in parent ViewController.
ViewControllerRegistration.h
#protocol RegistrationViewControllerDelegate;
#interface ViewControllerRegistration : UIViewController
#property (nonatomic, weak) id<RegistrationViewControllerDelegate> delegate;
- (IBAction)registerNewUser:(id)sender;
#end
// 3. Definition of the delegate's interface
#protocol RegistrationViewControllerDelegate <NSObject>
-(void)loginResult:(NSString*)loginData;
#end
ViewControllerRegistration.m
- (void)registerNewUser:(id)sender {
id<RegistrationViewControllerDelegate> strongDelegate = self.delegate;
// Our delegate method is optional, so we should
// check that the delegate implements it
if ([strongDelegate respondsToSelector:#selector(loginResult:)]) {
[strongDelegate loginResult: #"#WHY YOU NOT BEING CALLED?"];
}
Parents:
ViewController.h
#import "ViewControllerRegistration.h"
#interface ViewController : UIViewController <GPPSignInDelegate,FBSDKLoginButtonDelegate,RegistrationViewControllerDelegate>
#end
ViewController.m
#implementation ViewController
#synthesize signInButton;
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
ViewControllerRegistration *detailViewController = [[ViewControllerRegistration alloc] init];
// Assign self as the delegate for the child view controller
detailViewController.delegate = self;
}
//Local Strategy
- (IBAction)navigateToLocalSignUpNavBtn:(id)sender {
[self performSegueWithIdentifier:#"SegueRegisterUserAction" sender:self];
}
// Implement the delegate methods for RegistrationViewControllerDelegate
-(void)loginResult:(NSString*)loginData{
NSLog(#"I am called");
//^Above is never printed. That means delegate method is never called
}
Please note, my parent view controller is embedded in a navigation controller.
The delegate method is never called. Tried debugging, but in vain.
The view controller you are creating in viewDidLoad isn't the same one that you will be segueing to. It's another instance that will be deallocated at the end of the method. You need to access the correct instance in prepareForSegue and set the delegate there.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"SegueRegistrationUserAction"]) {
[(ViewControllerRegistration *)segue.destinationViewController setDelegate:self];
}
}
Yesterday, I had explained this in length on this thread. Please take a look and let me know if you have any specific question post that. I hope this would help you.
Related
I am trying to get a string from a view controller to another using delegate method.But the delegate method is not getting called.Below is the code
#protocol CustomDelegate<NSObject>
-(void)didDataRecieved;
#end
#interface CustomController:UIViewController
#property id<CustomDelegate>delegate;
#property(retain,nonatomic)NSString *string;
#end
#implementaion CustomController
-(void)viewDidLoad
{
string=#"hello";
if([self.delegate respondsToSelector#selector(didDataRecived)]) {
[self.delegate didDataRecieved];
}
}
-(IBACTION)gotoViewController
{
ViewController *view=[self.storyboard instantiateViewController:#"View"];
[self.navigationController pushViewController:view aniamted:YES];
}
#end
#interface ViewController:UIViewController<CustomDelegate>
#property (nonatomic,retain)CustomController *cust;
#end
#implementation ViewController
-(void)viewDidLoad
{
self.cust=[[CustomController alloc]init];
self.cust.delegate=self;
}
-(void)didDataRecieved
{
NSLog(#"data %#",self.cust.string);
}
#end
Can anyone point out where am going wrong...plz help.
edited the code..tried this way too.
if([self.delegate respondsToSelector#selector(didDataRecived)]){
[self.delegate didDataRecieved];
}
I will give you the sample coding.Customize the below code.
Here we have two view controllers.
ViewController
and
SecondViewController
in SecondViewController
.h
#import <UIKit/UIKit.h>
#class SecondViewController;
#protocol SecondViewControllerDelegate <NSObject>
- (void)secondViewController:(SecondViewController *)secondViewController didEnterText:(NSString *)text;
#end
#interface SecondViewController : UIViewController
#property (nonatomic, assign)id<SecondViewControllerDelegate> delegate;
#property (nonatomic, strong) IBOutlet UITextField *nameTextField;//It must connect as outlet connection
- (IBAction)doneButtonTapped:(id)sender;
#end
.m
#import "SecondViewController.h"
#interface SecondViewController ()
#end
#implementation SecondViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}
//Either use NSNotification or Delegate
- (IBAction)doneButtonTapped:(id)sender;
{
//Use Notification
[[NSNotificationCenter defaultCenter] postNotificationName:#"passingDataFromSecondViewToFirstView" object:self.nameTextField.text];
//OR Custom Delegate
[self.delegate secondViewController:self didEnterText:self.nameTextField.text];
[self.navigationController popViewControllerAnimated:YES];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
in ViewController
.h
#import <UIKit/UIKit.h>
#import "SecondViewController.h"
#interface ViewController : UIViewController<SecondViewControllerDelegate>
#property (nonatomic, strong) IBOutlet UILabel *labelName; //You must connect the label with outlet connection
- (IBAction)gotoNextView:(id)sender;
#end
.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
//addObserver here...
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(textFromPreviousViewControllerNotificationReceived:) name:#"passingDataFromSecondViewToFirstView" object:nil];
// Do any additional setup after loading the view, typically from a nib.
}
//addObserver Method here....
- (void)textFromPreviousViewControllerNotificationReceived:(NSNotification *)notification
{
// set text to label...
NSString *string = [notification object];
self.labelName.text = string;
}
- (IBAction)gotoNextView:(id)sender;
{
//If you use storyboard
SecondViewController *secondViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"SecondViewController"];
//OR If you use XIB
SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
secondViewController.delegate = self;
[self.navigationController pushViewController:secondViewController animated:YES];
}
//Calling custom delegate method
- (void)secondViewController:(SecondViewController *)secondViewController didEnterText:(NSString *)text
{
self.labelName.text = text; //Getting the data and assign the data to label here.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
For your understanding the code I create a simple passing data from one second view controller to first view controller.
First we navigate the view from first view controller to second view controller.
After that we send the data from second view controller to first view controller.
NOTE : You can either use NSNotification or Custom Delegate method for sending data from One View Controller to Other View Controller
If you use NSNotification, you need to set the postNotificationName for getting data in button action method.
Next you need to write addObserver in (sending data to your required View Controller) ViewController and call the addObserver method in same View Controller.
If you use custom delegate,
Usually we go with Custom Protocol Delegate and also we need to Assign the delegate here.
Very importantly we have to set the Custom Delegate Method in the Second View Controller.Because where we send the data to first view controller once we click the done button in second view controller.
Finally we must call the Custom Delegate Method in First View Controller, where we get the data and assign that data to label.Now you can see the passed data using custom delegate.
Likewise you can send the data to other view controller using Custom Delegate Methods
how you pushing your second controller? i cant see.
but your code working for me.
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
ViewController1 *vc = [ViewController1 new];
vc.delegate = self;
[self presentViewController:vc animated:YES completion:nil];
}
-(void)didDataRecieved
{
NSLog(#"recieved");
}
#end
Look at the following code.
In CusFormViewController.h
#interface CusFormViewController : CusBaseViewController
#protocol CusFormViewControllerDelegate <NSObject>
-(void)ticketCreated:(NSString*)ticketID;
-(void)ticketFormRenderingFinished;
#end
#property (nonatomic, weak) id<CusFormViewControllerDelegate> delegate;
In CusFormViewController.m
if ([self.delegate respondsToSelector:#selector(ticketFormRenderingFinished)])
[self.delegate ticketFormRenderingFinished];
if ([self.delegate respondsToSelector:#selector(ticketCreated:)])
[self.delegate ticketCreated:ticket_id];
In ViewController.m
#import "CusFormViewController.h"
#interface ViewController ()<CusFormViewControllerDelegate>
- (void)viewDidLoad {
[super viewDidLoad];
CusFormViewController *formVC = [[CusFormViewController alloc] init];
[formVC setDelegate:self];
}
-(void)ticketCreated:(NSString*)ticketID{
NSLog(#"ticket created.");
}
-(void)ticketFormRenderingFinished{
NSLog(#"ticket form rendered.");
}
The ticketCreated & ticketFormRenderingFinished are not being called.
Most common reason for delegate method not being called is dealing with incorrect objects.
Ensure that CusFormViewController object created from
ViewController is the same which you are presenting on screen and
that the delegate is being set on the same object. I truly believe
you are creating a new CusFormViewController object and setting
delegate on that.
In CusFormViewController, before calling delegate, check the
existence of delegate as well. This is a safety check, you can also put a
NSLog statement to double check if your delegate exists or not. You
are failing here.
If you are segueing from ViewController to CusFormViewController then you set delegate in prepareForSegue: and not in viewDidLoad.
As a side note, put a NSLog statement in viewDidLoad of your CusFormViewController and print self.delegate to check the property setting.
Your controller formVC is dealloced after the function viewDidLoad executed. Create strong reference on your formVC for example like this:
#interface ViewController ()<CusFormViewControllerDelegate>
{
CusFormViewController *_formVC;
}
- (void)viewDidLoad {
[super viewDidLoad];
_formVC = [[CusFormViewController alloc] init];
[formVC setDelegate:self];
}
Hey try to create instance of CusFormViewController using below method
CusFormViewController * _formVC=[[UIStoryboard storyboardWithName:storyboardName bundle: nil]instantiateViewControllerWithIdentifier:#"IDENTIFIER_OF_YOUR_ CusFormViewController"];
I ultimately want to write an iOS app incorporating ALAssetsLibrary, but as a first step toward understanding delegation, I'm trying to pass a simple message between two view controllers. For some reason, I can't seem to get the message to pass. In particular, the delegate object (derpy) doesn't appear to exist (if(self.derpy) returns NO)).
I asked the same question on the Apple forums and was told that I should be using segues and setting properties / calling methods using self.child instead, but that seems strange. If I were to pass messages using the parent / child properties, would I still be able to create my views in Interface Builder? Once I have my two views set up, say inside a UINavigationController, I'm not sure how to actually "wire them up" so I can pass messages between them. Sorry if the question is overly broad.
Here's the controller I'm declaring the protocol in (called PickerViewController):
Interface:
#import <UIKit/UIKit.h>
#import <AssetsLibrary/AssetsLibrary.h>
#protocol DerpDelegate <NSObject>
#required
- (void) test;
#end
#interface PickerViewController : UIViewController
#property (nonatomic, assign) id<DerpDelegate> derpy;
#end
Implementation:
#import "PickerViewController.h"
#interface PickerViewController ()
#end
#implementation PickerViewController
- (void)viewDidLoad
{
[super viewDidLoad];
if (self.derpy) { // If the delegate object exists
[self.derpy test]; // send it this message
} else {
NSLog(#"Still not working."); // This always returns (i.e., self.derpy doesn't exist)
}
}
Delegate controller (MainViewController) interface:
#import <UIKit/UIKit.h>
#import "PickerViewController.h"
#interface MainViewController : UIViewController <DerpDelegate> // public promise to implement delegate methods
#property (strong, nonatomic) PickerViewController *picker;
- (void) test;
#end
And lastly, the delegate controller (MainViewController) implementation:
#import "MainViewController.h"
#import "PickerViewController.h"
#interface MainViewController ()
#end
#implementation MainViewController
// Here's that method I promised I'd implement
- (void) test{
NSLog(#"Test worked."); // This never gets called
}
- (void)viewDidLoad {
[super viewDidLoad];
self.picker.derpy = self;
//lazy instantiation
- (PickerViewController *) picker{
if(!_picker) _picker = [[PickerViewController alloc]init];
return _picker;
}
EDIT: Many thanks to rydgaze for pointing me in the right direction with self.picker.derpy = self, but for some reason, things still aren't working properly. Importantly, once that property has been set, if(self.picker.derpy) returns YES from MainViewController. But if(self.derpy) is still returning NO when called from inside the PickerViewController's viewDidLoad. How can the property exist and not exist at the same time?
You need to be sure that you're setting the delegate on the instance of the view controller that you put on screen. If you're using a navigation controller and segues to go between MainViewController and PickerViewController, then you should set the delegate in prepareForSegue:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
self.picker = (PickerViewController *)segue.destinationViewController;
self.picker.derpy = self;
}
You need to populate the delegate first.
Basically, your MainViewController shoudl at somepoint do a
picker.derpy = self;
Then when the delegate fires in PickerViewController, the callback will happen.
Edit:
A good practice is to do something like in PickerViewController
#property (nonatomic, assign) id<DerpDelegate > derpy;
and in your MainViewController indicate that you will implement the delegate
#interface MainViewController : UIViewController<DerpDelegate>
Eventually in your implementation of MainViewController
You will have something like
picker = [[PickerViewController alloc]init];
picker.derpy = self;
[picker doYourThing];
Once picker is all done, it may want to return results using the delegate.
i have created a delegate for my project the code of my main view is
VedantViewController.h
#protocol VedantDelegate;
#interface VedantViewController : UIViewController
{
id <VedantDelegate> delegate;
}
//some other outlets
#property(nonatomic, assign) id <VedantDelegate> delegate;
#protocol VedantDelegate <NSObject>
- (void)display:(NSString *)JSONResponse;
#end
VedantViewController.m
#synthesize delegate;
[delegate display:jsonResponse];
SecondViewController.h
#interface SecondViewController : UIViewController<VedantDelegate>
- (void)display:(NSString *)JSONResponse;
SecondViewController.m
- (void)display:(NSString *)string
{
}
but this code is not working properly
when i debug the code using breakpoints the code reaches the
[delegate display:abc];
but it does not calls display function in SecondViewController.m file
i think my code is right but some mistake that i can't recognize
let me explain you the flow of my project this could be the problem
by default the VedantViewController view is launched
after that when the show button is click it calls the SecondViewController view in the view these is list button that calls the function in VedantViewController this function then calls the delegate method that is [delegate display:jsonResponse];
Thanks in Advance,
Arun.
The view controller which is confirming with the protocol, should have this line in the viewDidLoad or anywhere you are making the object of that viewController
Add this line in SecondViewController.m
VedantViewControllerObject.delegate = self;
#protocol VedantDelegate;
#interface VedantViewController : UIViewController{
id<VedantDelegate> delegate;
}
//some other outlets
#property(nonatomic,assign) id<VedantDelegate> delegate;
#protocol VedantDelegate <NSObject>
-(void)displayAccounts:(NSString *)JSONResponse;
-(void)display:(NSString *)JSONResponse;
#end
and also set delegate to object of VedantViewControllerObject class as self in SecondViewController class and the object of VedantViewControllerObject class should be initialized and allocated.
vedantViewControllerObject.delegate = self;
In your VedantViewController.h file you declared method as below
-(void)displayAccounts:(NSString *)JSONResponse;
But you are calling it [delegate display:jsonResponse];
You just try to call
[delegate displayAccounts:jsonResponse];
And in SecondViewController.m
(void)displayAccounts:(NSString *)string{
}
There are some issues in your code:
set the delegate in second view controller
vedViewObject.delegate = self;
You added displayAccounts method in delegate and calling display method, that can cause issues. If that methods are not implemented in the delegate class.
Add if condition like: if(delegate)[delegate displayAccounts:jsonResponse];
I am trying to make a custom protocol that i hope somebody might help with.
I have a mainViewController (mainVC) that has a label. That label needs to be updated with a string when i press a button in edwwVC.
I am using ARC and storyboard.
The problem is when i press the Done Button on the edwwVC, the "done" method is called BUT the delegate method is not called in mainVC.
Whereas, if i call the done method VIA the mainVC, then the done method is called AND the delegate method. So I can see the connection is there, I just do not understand why the delegate method is not called when i press the done button in the edwwVC.
I imagine it has something to do with the init of the edwwVC. Because it is already initiated by storyboard, so it looks to me as if I am initializing it again the in the viewDidLoad method of the mainVC. But that is how far i got :)
Thanks in advance!
edwwVC.h
#import <UIKit/UIKit.h>
#import "IIViewDeckController.h"
#class EDWWViewController;
#protocol EDWWViewControllerDelegate <NSObject>;
#optional
- (void)edwwVCDidFinish:(EDWWViewController *)edwwVC;
#end
#interface EDWWViewController : UIViewController <IIViewDeckControllerDelegate> {
__weak id<EDWWViewControllerDelegate> delegate;
NSMutableArray *edwwPoints;
}
#property (weak) id<EDWWViewControllerDelegate> delegate;
#property (weak, nonatomic) IBOutlet UITableView *theTableView;
#property (strong, nonatomic) NSString *testString;
- (IBAction)done:(id)sender;
- (IBAction)add:(id)sender;
#end
edwwVC.m:
#pragma mark - delegate method
- (IBAction)done:(id)sender {
testString = #"This is the test string!";
[delegate edwwVCDidFinish:self];
[self.viewDeckController closeRightViewAnimated:YES];
NSLog(#"Done pressed");
}
MainVC.m:
- (void)viewDidLoad
{
[super viewDidLoad];
edwwViewController = [[EDWWViewController alloc] init];
edwwViewController.delegate = self;
}
- (void)edwwVCDidFinish:(EDWWViewController *)edwwVC {
edwwLabel.text= edwwVC.testString;
NSLog(#"delegate method called");
}
Remove the line ...
__weak id<EDWWViewControllerDelegate> delegate;
From the .h and change the line...
[delegate edwwVCDidFinish:self];
to...
[self.delegate edwwVCDidFinish:self];
In the .m.
That should sort it.
The way you have it set up the ivar delegate is not the same as the property delegate (which is actually an ivar called _delegate) (thanks #Joris Kluivers, just adding for clarity). They are pointing to different things.
If you add a breakpoint where you are calling the delegate method I think you'll find that delegate is nil. Whereas _delegate (or self.delegate) is not nil.
::EDIT::
Ahh... just spotted the second bit too.
If you are setting up the edwwvc in storyboard then you should be alloc initing it too.
If you are segue-ing to the edwwvc then you should intercept the segue in mainVC.m like this...
- (void)prepareForSegue: //blah the rest of the name...
{
if ([segue.identifier isEqualToString:#"the name of your segue"])
{
EDWWViewController *controller = segue.destinationViewController;
controller.delegate = self;
}
}
This will take the controller that you are pushing to from the storyboard and set the delegate to it.
:: ANOTHER EDIT ::
If EDWWVC is inside a containerViewController then you can do this inside viewDidLoad in MainVC.m...
- (void)viewDidLoad
{
// other stuff...
for (UIViewController *controller in self.childViewControllers) {
if ([controller isKindOfClass:[EDWWViewController class]]) {
EDWWViewController *edwwvc = (EDWWViewController*)controller;
eddwvc.delegate = self;
}
}
}
You may find this code has to go in viewDidAppear or something but I think viewDidLoad shouldd work just fine.
You may actually be able to set the delegate property directly by using the storyboard to (but I'm not 100% certain on this).
The answer was in the containerVC of both controllers.
Where i initialized the view controllers: the viewDidLoad of the containerVC m file:
- (void)viewDidLoad
{
[super viewDidLoad];
mainVC = (MainViewController *)[self.storyboard instantiateViewControllerWithIdentifier:#"MainVC"];
edwwVC = (EDWWViewController *)[self.storyboard instantiateViewControllerWithIdentifier:#"EDWWVC"];
//THIS LINE WAS MISSING
edwwVC.delegate = mainVC;
self.centerController = mainVC;
self.rightController = edwwVC;
}
BUT guys thanks for the help! :) Appreciate it got me in the right direction! :) THANKS! :)