[offline] filtering entities from the database

odata API $filter.m

-(void)fetchContactsWithCompletion:(void(^)(NSArray *entities))completion {
    
    NSString *resourcePath = @"ContactCollection?$filter=length(company) gt 0 and length(function) gt 0";
    
    [self scheduleRequestForResource:resourcePath withMode:SODataRequestModeRead withEntity:nil withCompletion:^(NSArray *entities, id<SODataRequestExecution> requestExecution, NSError *error) {
        
        if (entities) {
            
            completion(entities);
            
        } else {
            
            NSLog(@"did not get any entities, with error: %@", error);
        }
    }];
}