how can i check NSNumber is null? - iphone

Question

NSDictionary *regionDict = (NSDictionary *) region;
NSNumber *lat = [regionDict objectForKey:#"lat"];
//[latitude addObject:lat];
NSNumber *lng = [regionDict objectForKey:#"lng"];
//[longitude addObject:lng];
NSLog(#"%#%#%#",lat,lng,titles);
if(lat == [NSNumber numberWithFloat:0.00] && lng == [NSNumber numberWithFloat:0.00])
{
NSLog(#"%#%#%#",lat,lng,titles);
}
else
{
CLLocationCoordinate2D coord;
coord.latitude =lat.doubleValue;
coord.longitude =lng.doubleValue;
MapViewAnnotation *annotation =[[MapViewAnnotation alloc]initWithTitle:titles AndCoordinate:coord];
[self.mapView addAnnotation:annotation];
}
if condition is not satisfied because of NSNumber not check with null value.
what is the way i can check?
Tell me possible ways.. for checking null.

Answer 1

You can check if an object is null by doing
if ([myObject isKindOfClass:[NSNull class]])
But if you want to check if a float boxed in a NSNumber is zero, you can do
if (lng.floatValue == 0. && lat.floatValue == 0)

Answer 2

I've been checking if NSDecimalNumber was null using:
if (decimalNumber == nil)
This is working great for me.

Answer 3

NSDictionary *regionDict = (NSDictionary *) region;
NSNumber *lat;
if([regionDict objectForKey:#"lat"] == [NSNull null])
{
lat = 0;
}
else
{
lat = [regionDict objectForKey:#"lat"];
}
NSNumber *lng;
if([regionDict objectForKey:#"lng"] == [NSNull null] )
{
lng=0;
}
else
{
//[latitude addObject:lat];
lng = [regionDict objectForKey:#"lng"];
}
//[longitude addObject:lng];
if(lat.floatValue == 0.00 && lng.floatValue == 0.00)
{
NSLog(#"%#%#%#",lat,lng,titles);
}
else
{
NSLog(#"%#%#%#",lat,lng,titles);
CLLocationCoordinate2D coord;
coord.latitude =lat.doubleValue;
coord.longitude =lng.doubleValue;
MapViewAnnotation *annotation =[[MapViewAnnotation alloc]initWithTitle:titles AndCoordinate:coord];
[self.mapView addAnnotation:annotation];
}

Answer 4

I'm not quite clear what you want to check. Depending on your JSON data, you will get one of the following:
myObject == nil - the object isn't there at all.
myObject == [NSNull null] - the JSON data is "null" without the quotes
myObject.doubleValue == 0.0 - the JSON data contained a number 0 or 0.0
Note that trying to read doubleValue will crash if the JSON data was "null", so that needs checking first. Comparing
myObject == [NSNumber numberWithDouble:0.0]
isn't going to work, because that just compares object pointers. Would be a very huge coincidence if this was actually the same object.

Answer 5

[obj isKindOfClass:[NSNull class]]