Custom delegate method doesn't get called

Question

So, I'm following this answer in trying to pass data between two classes in an iOS project without storyboards. I'm trying to abstract all my server calls in a different class, so the ViewControllers don't get too cramped. I have an OfferRequest class, which handles the server requests and declares the protocol:

@protocol OfferRequestDelegate <NSObject>

-(void)addOfferRequest: (OfferRequest *)request dataFromRequest: (NSMutableArray *)data;

@end

@interface OfferRequest : NSObject <LocationManagerDelegate, NSURLConnectionDataDelegate>

@property (nonatomic, weak) id <OfferRequestDelegate> delegate;
@end

The idea is to call addOfferRequest: dataFromRequest in connectionDidFinishLoading, set the data as the result from the request and pass it on to the ViewController.

In OfferRequest.m:

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {

    NSMutableArray *result = [NSJSONSerialization JSONObjectWithData:receivedData options:kNilOptions error:nil];
    [self.delegate addOfferRequest:self dataFromRequest:result];

}

I declare my ViewController as a delegate for the OfferRequest:

@interface CategorySuggestionViewController : UIViewController <OfferRequestDelegate>

Initialize the OfferRequest object and set it's delegate:

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    offer = [OfferRequest new];
    offer.delegate = self;
}

And then implement the delegate method:

-(void)addOfferRequest:(OfferRequest *)request dataFromRequest:(NSMutableArray *)data {
    NSLog(@"received data = %@", data);
}

But it never gets called. What am I missing ?

Could you paste the code with the the creation of connection and the request for that connection? -Off topic- Maybe you should consider using blocks. — Adi Pop, Dec 09 '14 at 10:27
@AdiPop I don't think it is relevant, since the data in OfferRequest is correctly set. Also: could you please point me to an explanation how to use blocks in this situation ? I'm not very experienced with objective c. — smeshko, Dec 09 '14 at 10:30
Did you check inside connectionDidFinishLoading if delegate is not nil ? — Adi Pop, Dec 09 '14 at 10:31
@AdiPop Hm, yes, it is nil. I have `@synthesize delegate;` at the beginning of `OfferRequset.m` and I thought it gets initialized there. How and where should I initialize it ? — smeshko, Dec 09 '14 at 10:34
@smeshko Are you allocating offer in any other place apart from viewDidLoad? — thavasidurai, Dec 09 '14 at 10:40
@thavasidurai No, `offer` is a property that I use throughout the ViewController, I don't need any other `OfferRequest` instances. The weird thing is, I call the `OfferRequest` method in `didSelectRowAtIndexPath` and set the delegate in `viewDidLoad`, so you'd expect, that the delegate is set before it is needed in `OfferRequest`. Or am I seeing it wrong ? — smeshko, Dec 09 '14 at 10:42
initiliaze your offer =[[OfferRequest alloc]init]; instead of offer = [OfferRequest new] — karthikeyan, Dec 09 '14 at 10:44
@karthikeyan Still doesn't work: `delegate` is still Nil in `connectionDidFinishLoading` and the delegate method doesn't get called. — smeshko, Dec 09 '14 at 10:46
@smeshko if possible can you please post code which you wrote in didSelectRowAtIndexPath? — thavasidurai, Dec 09 '14 at 10:48
if connectionDidFinishLoading get called,check your result array whether having value or not — karthikeyan, Dec 09 '14 at 10:49
I think that the instance of CategorySuggestionViewController is deallocated that will explain that the delegate is nil. — Adi Pop, Dec 09 '14 at 12:14

score 0 · Answer 1 · answered Dec 09 '14 at 11:09

try this...

your OfferRequest class like below i have given name it as connectionClass

connectionClass.h

@protocol connectionDelegate <NSObject>
-(void)connectionSucceed:(NSData *)data;
-(void)connectionFailed:(NSError *)error;
@end

#import <Foundation/Foundation.h>

@interface connectionClass : NSObject
{
    id<connectionDelegate> delegate;
    NSMutableData *receivedData;
    NSString *encodedString;
    NSMutableURLRequest *theRequest;
    NSURL *url;
    NSString *length;
    NSURLConnection *Connect;

}
@property(nonatomic, retain) id<connectionDelegate> delegate;
@property(nonatomic, retain) NSMutableData *receivedData;
- (void)connectionWithURL:(NSString *)URL;
@end

connectionClass.m

#import "connectionClass.h"

@implementation connectionClass
@synthesize delegate, receivedData;
- (void)connectionWithURL:(NSString *)URL
{
    url=[[NSURL alloc] initWithString:[self urlencode:URL]];
    theRequest= [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:60];
    [theRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    length = [NSString stringWithFormat:@"%lu", (unsigned long)[URL length]];
    [theRequest setValue:length forHTTPHeaderField:@"Content-Length"];
    [theRequest setHTTPMethod:@"POST"];

    [theRequest setHTTPBody:[URL dataUsingEncoding:NSUTF8StringEncoding]];

    Connect = [NSURLConnection connectionWithRequest:theRequest delegate:self];

    if (Connect)
    {
        self.receivedData = [NSMutableData data];
    }
    else
    {
        NSError *error;
        [self.delegate connectionFailed:error];
    }
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [self.receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [self.receivedData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    [self.delegate connectionSucceed:self.receivedData];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    [self.delegate connectionFailed:error];
}
-(NSString *) urlencode: (NSString *) string
{
    encodedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)string, NULL, (CFStringRef)@"", kCFStringEncodingUTF16));
    return encodedString;
}


@end

don't forget to import your connectionclass and delegate

@interface yourclass : UIViewController<connectionDelegate>

Initialize the OfferRequest object and set it's delegate:

-(void)viewWillAppear:(BOOL)animated
{
    connection = [[connectionClass alloc]init];
    connection.delegate = self;
     [connection connectionWithURL:[NSString stringWithFormat:@"pass your url here"]];
}

The delegate method will have your values

-(void)connectionSucceed:(NSData *)data
{
    NSError *error;
    self.dictionary = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
    //nslog your data
}

//Connection failure
-(void)connectionFailed:(NSError *)error
{
  //handle error message
}

you set retain for connectionDelegate it is not better practice it should be weak — thavasidurai, Dec 09 '14 at 11:16
@thavasidurai thanks for your suggestion.But it will retain a value,when using multiple connection so i used retain property — karthikeyan, Dec 09 '14 at 11:20

score 0 · Accepted Answer · answered Dec 12 '14 at 11:00

Ok, I don't know where the problem exactly was, but what I did to fix it, was to create a new init method, where I pass the delegate:

-(instancetype)initWithDelegate: (id<OfferRequestDelegate>) delegate {
    self = [super init];

    if (self) {
        self.delegate = delegate;
    }

    return self;
}

So I initialize the OfferRequest object in the VC and pass self and now it works.

score -2 · Answer 3 · edited Dec 09 '14 at 12:13

-2

I guess delegate should be a pointer object and not the object.

It may be help you

@property (nonatomic, weak) NSObject <OfferRequestDelegate> *delegate;

and make should your delegate is been set, i.e. make sure your code below is getting called.

 [self.delegate addOfferRequest:self dataFromRequest:result];

edited Dec 09 '14 at 12:13

karthikeyan

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answered Dec 09 '14 at 11:15

Rajesh

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Custom delegate method doesn't get called

3 Answers3