First I convert BOOL value to NSNumber in order to put it into NSUserDefaults. Later I would like to retrieve the BOOL value from the NSUserDefaults, but obviously I get NSN
You currently compare two pointers. Use NSNumbers methods instead to actually compare the two:
if([someNSNumberValue isEqualToNumber:[NSNumber numberWithBool:NO]]) {
// ...
}
To get the bool value from a NSNumber use -(BOOL)boolValue:
BOOL b = [num boolValue];
With that the comparison would be easier to read for me this way:
if([num boolValue] == NO) {
// ...
}