Enhance Readme

[nkanetka]

• Add documentation on the different ways the framework can be used

[vermont42]

Here is a proposed blurb. Various other changes to the readme would flow from this.

Your app might only need locations from a GPX file or CLLocation array. In this case, instantiate GpxLocationManager directly and use that. Example:

let gpxLocationManager = GpxLocationManager()
gpxLocationManager.setLocations(gpxFile: "Waterloo") // OR
gpxLocationManager.setLocations(locations: [locations])
gpxLocationManager.delegate = self
gpxLocationManager.startUpdatingLocations()

But your app might need device locations from CLLocationManager or locations from a GPX file or CLLocation array. For example, a run-tracking app's model might want to use CLLocationManager during actual runs but GpxLocationManager during development and testing. One approach for accomplishing this would be for the model to own an optional GpxLocationManager and an optional CLLocationManager. But this approach would result in repeated if checks, as show below.

let cLLocationManager: CLLocationManager?
let gpxLocationManager: GpxLocationManager?

if usingCLLocationManager {
  cLLocationManager = CLLocationManager()
  cLLocationManager.delegate = self
} else /* if usingGpxLocationManager */ {
  gpxLocationManager = GpxLocationManager()
  gpxLocationManager.setLocations(gpxFile: "Waterloo")
  gpxLocationManager.delegate = self
}

...

if usingCLLocationManager {
  cLLocationManager?.startUpdatingLocation()
} else /* if usingGpxLocationManager */ {
  gpxLocationManager?.startUpdatingLocation()
}

But there is a better way. LocationManager is a wrapper on a GpxLocationManager or a CLLocationManager. Simply instantiate the appropriate variant of LocationManager and use it like you would use a GpxLocationManager or CLLocationManager. Example:

let locationManager: LocationManager
if usingCLLocationManager {
  locationManager = LocationManager(type: .coreLocation)
} else /* if usingGpxLocationManager */ {
  locationManager = LocationManager(type: .gpxFile("Waterloo"))
}
locationManager.delegate = self

...

locationManager.startUpdatingLocation()