@interface School : NSObject

@property NSInteger level;

- (BOOL) isForKids;

@end

@implementation School
- (BOOL) isForKids {
    return _level == 3;
}

@end

School *mySchool = [[School alloc] init];
//set level to 3
mySchool.level = 3;
// expected boolean true but get false, why?
BOOL forKids = [mySchool isForKids];