@interface hogeViewController(){
isFlag
}

- (void)viewDidLoad {
    [super viewDidLoad];

    [self getFlag];
}

-(void) viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];

    if(isFlag){
        ...
    }else{
        ...
    }
}

-(void) getFlag{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    NSString *serverInfo_ = nil;
    serverInfo_ = [NSString stringWithFormat:@"https://%@", WebServerInfo];
    NSString *mediaApi = [serverInfo_ stringByAppendingFormat:@"/api/hoge/"];

    NSURL *url_ = [NSURL URLWithString:mediaApi];
    [request setHTTPMethod:@"GET"];

    [NSURLConnection sendAsynchronousRequest:request
                                    queue:[NSOperationQueue mainQueue]
                        completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
                            if(data){
                                isFlag = true;
                            }
                        }];
}