How Access instance Variable in Class method

I am a new iOS developer, i try to access instance variable in class method but i can't access.please give me some solution here is my code

h.file

@protocol ServiceProvideDelegate <NSObject>
@required
-(void)responeFromURL:(NSDictionary*)dicResponse;
@end

@interface AFNetworkServiceProvider : NSObject
{
   id <ServiceProvideDelegate> delegate;
}
@property (nonatomic,strong) id delegate;

+(NSDictionary*)getResponseFromURL:(NSURL*)url;
@end

m.file

@implementation AFNetworkServiceProvider
@synthesize delegate;
+(void)getResponseFromURL:(NSURL *)url
{
 @try
 {
    NSURLRequest *request=[NSURLRequest requestWithURL:url];
    AFHTTPRequestOperation *requestOperation=[[AFHTTPRequestOperation alloc]initWithRequest:request];
    requestOperation.responseSerializer=[AFJSONResponseSerializer serializer];

    [requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
    {
        if(delegate)
        {
          [delegate responeFromURL:responseObject]
       } 
    }
    failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"Response Error :- %@",[error localizedDescription] );
    }];
    [requestOperation start];    
}
@catch (NSException *exception)
{

}
@finally {

}
}

Try to Returne Response object using protocol method, but i get the error at if(delegate) unable to access instance variable in class method