Reason for change:

When mapping our dictionaries to our models MTLModel uses NSObject validateValue:forKey:error: If the properties is of type NSInteger and the value is nil this will return true, it will then attempt to setValue:forKey with the nil value and cause a crash.

Using NSNumber we protect ourselves against this.

It appears the initial message (when you open the app for the first time on the Watch but never on your phone) is confusing. It should be more clear than you need to open the iPhone app first and give the permissions in there

Crash on StationsRepository.m line 41 -[StationsRepository stationsForNetwork:withCompletionBlock:]

0  CoreFoundation                 0x22efefef __exceptionPreprocess + 126
1  libobjc.A.dylib                0x3144cc8b objc_exception_throw + 38
2  CoreFoundation                 0x22efef35 -[NSException initWithCoder:]
3  Foundation                     0x23b781a3 -[NSString stringByAppendingString:] + 90
4  CityBikesKit                   0x00268ab9 -[StationsRepository stationsForNetwork:withCompletionBlock:] (StationsRepository.m:41)
5  BikeCompass                    0x000deb3f -[CompassViewController displayStationInformation] (CompassViewController.m:87)
6  BikeCompass                    0x000dfd31 -[CompassViewController locationManager:didChangeAuthorizationStatus:] (CompassViewController.m:238)
7  BikeCompass                    0x000e31cb -[LocationManager locationManager:didChangeAuthorizationStatus:] (LocationManager.m:97)
8  CoreLocation                   0x235c2359 (null) + 21892
9  CoreLocation                   0x235be243 (null) + 5230
10 CoreLocation                   0x235b7d79 (null) + 972
11 CoreFoundation                 0x22ec4fd5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
12 CoreFoundation                 0x22ec4299 __CFRunLoopDoBlocks + 216
13 CoreFoundation                 0x22ec2dd3 __CFRunLoopRun + 1714
14 CoreFoundation                 0x22e0f201 CFRunLoopRunSpecific + 476
15 CoreFoundation                 0x22e0f013 CFRunLoopRunInMode + 106
16 GraphicsServices               0x2a6ee201 GSEventRunModal + 136
17 UIKit                          0x265b3a59 UIApplicationMain + 1440
18 BikeCompass                    0x000e2157 main (main.m:14)
19 libdyld.dylib                  0x319d8aaf start + 2

Your blog post about animations is pretty cool.

However I'm unable to compile using Xcode9.2. I also tried using Xcode9.0.1, but no luck.

Your code looks good.

func loadStations(forNetwork network: Network) {
        CityBikes.stations(forNetwork: network) { response in
            switch response {
            case .Success(let stations):
                self.stations = stations
                // Request the current user location
                self.locationManager.requestLocation()
            case .Failure(let error):
                print(error)
            }
        }
    }

The requestLocation is sooooo slow, like really slow. Fix it