변수가 @ (null) 인 것을 방지함으로써 충돌을 피할 수 있습니까?

Question

나는 응용 프로그램이 실행될 때 사용자 위치를 얻고 위치 변수가 @ (null) 인 경우 위 whit if 문을 방지합니다. 내 FirstViewController.h에서 :

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 
    locationManager = [[CLLocationManager alloc] init]; 
    locationManager.delegate = self; 
    locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; 
    [locationManager startUpdatingLocation]; 

} 

CLLocationManager *locationManager; 

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation 
{ 
    CLLocation *currentLocation = newLocation; 
    if (currentLocation != NULL) { 
     [(AppDelegate *)[[UIApplication sharedApplication] delegate] setLatitude:[NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude]]; 

     [(AppDelegate *)[[UIApplication sharedApplication] delegate] setLongitude:[NSString stringWithFormat:@"%.8f", currentLocation.coordinate.longitude]]; 
    } 
} 

내 SecondViewController에서이 if 문으로

-(void) GettingGlobalVariables{ 
    NSString *UsersCurrentLatitude = [(AppDelegate *)[[UIApplication sharedApplication] delegate] latitude]; 
    NSString *UsersCurrentLongitude = [(AppDelegate *)[[UIApplication sharedApplication] delegate] longitude]; 

    NSNumberFormatter * singsingsing = [[NSNumberFormatter alloc] init]; 
    [singsingsing setNumberStyle:NSNumberFormatterDecimalStyle]; 
    NSNumber * myNumberLatitude = [singsingsing numberFromString:UsersCurrentLatitude]; 


    NSNumberFormatter * sheCameToMeOneMorning = [[NSNumberFormatter alloc] init]; 
    [sheCameToMeOneMorning setNumberStyle:NSNumberFormatterDecimalStyle]; 
    NSNumber * myNumberLongitude = [sheCameToMeOneMorning numberFromString:UsersCurrentLongitude]; 
     NSLog(@"mynumberlatitude:%@,mynumberlongitude:%@",myNumberLongitude,myNumberLatitude); 
    if (!myNumberLatitude) { 
     NSLog(@"location variables are null"); 
     TabBar *TB =[[TabBar alloc]init]; 
     [TB performSelector:@selector(viewDidLoad)]; 
     [TB performSelector:@selector(locationManager:didUpdateToLocation:fromLocation:)]; 
     [self performSelector:@selector(GettingGlobalVariables)]; 

    } 
} 

변수가 null 응용 프로그램 호감이다. 어떠한 제안? NSLog`만약 (! myNumberLatitude) { (@ "위치 변수가 null입니다"); :이 같은

Answer 1

사용

if (currentLocation != [NSNull null] | currentLocation !=nil) { 
     //write your code here. 
    }