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];
Related
So I am calling delegate function but some how its not getting called, I tried everything from all the other similar threads but nothing works. It looks all good but the method is still not called. here is my code below -
So i created protocol like this -
AuthViewController.h
#class AuthViewController;
#protocol AuthViewControllerDelegate <NSObject>
- (void)updateNavigation:(NSString*)pageType
message:(NSString*)message;
#end
created a property -
#property (nonatomic, weak)id delegate;
And called the function in AuthViewController.m -
[self.delegate updateNavigation:#"xx" message:#"xx"];
Then in other class -
AssociateViewController.h
#interface AssociateViewController : UIViewController <AuthViewControllerDelegate>
#property (nonatomic, strong)AuthViewController *vc;
#End
AssociateViewController.m
First set the delegate in a button action or viewWillAppear(I tried both)-
self.vc = [[AuthViewController alloc] init];
self.vc.delegate = self;
And the here is the method which is somehow never called :( -
- (void)updateNavigation:(NSString*)pageType
message:(NSString*)message;
{
//method to do
}
Any help would be much appreciated. Thanks!
I have written protocol in a view controller, and implement it in AppDelegate, and when I call delegate function from view controller, the delegate function is not called. Below is my code -
In class AuthenticationViewController -
#class AuthenticationViewController;
#protocol ApplicationTiomeoutDelegate <NSObject>
-(void) addObserverForTimeout;
#end
And call this function using delegate -
[self.appTimeoutDelegate addObserverForApplicationTimeout];
And in AppDelegate, I have implemented this protocol like this -
#interface AppDelegate () <ApplicationTiomeoutDelegate>
#end
And then set delegate to self -
AuthenticationViewController *timeoutDelegate = [[AuthenticationViewController alloc] init];
[timeoutDelegate setAppTimeoutDelegate:self];
And implemented delegate function as well in AppDelegate, which is never called somehow -
-(void) addObserverForApplicationTimeout{
// this function is never called
}
I am not sure what is not correct here.
AppDelegate being a singleton need not have the ApplicationTiomeoutDelegate protocol invocation. You can directly invoke addObserverForTimeout
You create method in your appdelegate, you can directly call it wherever you want with instance of appdelegate.
For your question, check this below
Where are creating instance for Your delegate and where are calling your delegate form your viewcontroller, it is used to communicate between two class, it should have reference of protocol.
try this
Your viewcontroller.h
#protocol customDelegate;
#import <UIKit/UIKit.h>
#import "CustomTableViewCell.h"
#interface ViewController : UIViewController<UITableViewDelegate>
{
IBOutlet UITableView *mainTableView;
}
#property (nonatomic,strong) id <customDelegate> delegate;
#end
#protocol customDelegate <NSObject>
-(void)method;
#end
ViewController.m
- (void)viewDidLoad {
[self.delegate method];
}
Your app delegate
#interface AppDelegate () <customDelegate>
#end
Your didfinishlaunghing
viewController = [[ViewController alloc]initWithNibName:#"ViewController" bundle:nil];
viewController.delegate = self;
and implement method:
-(void)method{
NSLog(#"calling");
}
I want to develop Custom Connection Class by which I can make API calls using it. I do not want to use any third party apis like afhttprequest or asihttp.
I want to develop my self this type of delegate. I have searched much things but I do not have much idea in CustomDelegates.
I wrote one example of custom delegate.
From ViewController.m we call method with two number for addition of another class (Addition class)
Addition class will add these two number and call delegate method so we can get answer of that two number in ViewController using custom delegate.
Addition.h
#import <Foundation/Foundation.h>
// write protocal for this class
// you can give any name of that protocol
#protocol AdditionDelgate <NSObject>
// delegate method of this delegate
-(void)answerOfTwoNumberAddition:(int)ans;
#end
#interface Addition : NSObject
{
}
// set property of that protocol, so using that we can call that protocol methods (i.e. ansOfYourAns)
#property (nonatomic, weak) id <AdditionDelgate> delegate;
-(void) addThisNumber:(int) firstNumber withSecondNumber:(int)secondNumber;
#end
Addition.m
#import "Addition.h"
#implementation Addition
-(void)addThisNumber:(int)firstNumber withSecondNumber:(int)secondNumber
{
int ans = firstNumber + secondNumber;
// call delegate method of "AdditionDelgate" protocol
// we already set delegate of viewController to this protocol
// so it will call viewController class "answerOfTwoNumberAddition" method
[self.delegate answerOfTwoNumberAddition:ans];
}
#end
ViewController.h
#import <UIKit/UIKit.h>
// import addition class
#import "Addition.h"
// set AdditionDelgate to class
#interface ViewController : UIViewController <AdditionDelgate>
#end
ViewController.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// creat object of class
Addition * additionObj = [[Addition alloc] init];
// set delegate as self to that so that methods delegate methods will call
additionObj.delegate = self;
// call method
[additionObj addThisNumber:2 withSecondNumber:3];
}
#pragma mark ----- Delegate method of Addition view ----
// this is delegate method of Addition class, it will call from "addThisNumber" method line of code
// ([self.delegate answerOfTwoNumberAddition:ans];)
-(void)answerOfTwoNumberAddition:(int)ans
{
NSLog(#"addition of two number is %d",ans);
}
#end
I hope it will help you
i'm trying to create my first delegate here's what i'm trying to do
at class called PAStepper.h i did this
#class PAStepper;
#protocol StepperDelegate <NSObject>
#required
-(void)didIncrement;
-(void)didDecrement;
#end
#interface PAStepper : UIControl
{
__weak id <StepperDelegate> stepperDelegate;
}
#property (nonatomic, weak) id <StepperDelegate> stepperDelegate;
#end
and synthized the property of course in the .m file
and then putten in the PAStepper.m the following in a method
[self.stepperDelegate didDecrement];
in the controller i want to take the delegate i did this
.h
#interface OCSideCartViewController : UIViewController<StepperDelegate>
.m
- (void)viewDidLoad
{
[super viewDidLoad];
PAStepper *stepper = [[PAStepper alloc]init];
stepper.stepperDelegate = self;
}
-(void)didIncrement{
NSLog(#"inc");
}
-(void)didDecrement{
NSLog(#"dec");
}
knowing that this class is viewController that contain a table that every cell have PAStepper .. all i wanted that the delegate call didIncrement and didDecrement whenever i press the buttons
When you call this method
[self.stepperDelegate didDecrement];
NSLog you stepperDelegate and ensure it is not null. Can you confirm the method which calls your delegate is being called?
you can call this in your pastapper.h file
if ([stepperDelegate respondsToSelector:#selector(didIncrement)])
{
[stepperDelegate performSelector:#selector(didIncrement)];
}
I can´t download the project, so i am guessing..
Is the Stepper in the Interface Builder?
If yes you don´t have to allocate it.
Make an Outlet Connection of the Stepper in the OCSideCartViewController.
Post this in OCSideCartViewController:
- (void)viewWillAppear:(BOOL)animated{
self.stepper.stepperDelegate = self;
[super viewWillAppear:animated];
}
If the Stepper is not an Outlet, you have to add it to your ViewControllers view after setting it´s bounds..
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.