we should also consider using the slightly more in vogue technique for private variables of using a class extension and properties going forward. It keeps the scope local but also gives you all the advantages of properties.

```
@interface DataRateRecorder()
@property(nonatomic, strong) NSTimer *tickTimer;   
@property(nonatomic, read ) double avgKBps[NUM_KBPS_DATA_POINTS];
@property(nonatomic,readwrite) NSUInteger circularIndex;
@property(nonatomic,readwrite) numBytesSinceTick;
@end

``