Maps, locations & sensors in ios

Transcription

1 Maps, locations & sensors in ios Sebastian Ernst, PhD Department of Applied Computer Science AGH University of Science and Technology

2 Displaying maps (ObjC) Maps are handled by MapKit and displayed using the MKMapView class (or its associated Map View storyboard object). It can be created programmatically: MKMapView *mymapview; mymapview = [[MKMapView alloc] initwithframe:self.view.bounds]; mymapview.maptype = MKMapTypeSatellite; mymapview.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleHeight; [self.view addsubview:mymapview];

3 Displaying maps (Swift) var mymapview = MKMapView(frame: self.view.bounds) mymapview.maptype = MKMapType.Satellite mymapview.autoresizingmask = UIViewAutoresizing.FlexibleWidth UIViewAutoresizing.FlexibleHeight self.view.addsubview(mymapview)

4 Displaying maps Alternatively, we can drag a MapView to the scene and create an appropriate outlet: (strong, nonatomic) IBOutlet MKMapView *mymapview; weak var mymapview: MKMapView!

5 Handling map view events Map views can produce various events. They can be handled by a function fulfilling the MKMapViewDelegate protocol. The possible events include: mapviewwillstartloadingmap: mapview:viewforannotation: mapviewwillstartlocatinguser: mapview:regiondidchangeanimated:

6 Using Core Location (ObjC) Use of various location sensors (GPS, GSM/Wi-Fi triangulation, magnetometer) is controlled by the Core Location framework. Its crucial element is the CLLocationManager class. Location events are handled by a delegate class with the CLLocationManagerDelegate protocol. if ([CLLocationManager locationservicesenabled]) { self.mylocationmanager = [[CLLocationManager alloc] init]; self.mylocationmanager.delegate = self; [self.mylocationmanager requestwheninuseauthorization]; [self.mylocationmanager startupdatinglocation]; }

7 Using Core Location (Swift) if (CLLocationManager.locationServicesEnabled()) { mylocationmanager = CLLocationManager() mylocationmanager.delegate = self mylocationmanager.requestwheninuseauthorization() mylocationmanager.startupdatinglocation() }

8 Getting permissions In ios 8, the CLLocationManger object must ask for permissions to use the location. This is achieved by calling the appropriate method: requestalwaysauthorization for apps which want to use location in the background, requestwheninuseauthorization for apps which only need the location when in use. Also, the description regarding what the location is needed for has to be added to the appropriate key in Info.plist (NSLocationAlwaysUsageDescription or NSLocationWhenInUseUsageDescription).

9 Handling location changes (ObjC) When the location is updated, the locationmanager:didupdatelocations: delegate method is called. It returns an array of CLLocation objects (at least one) the last element is the most recent location. - (void)locationmanager:(cllocationmanager *)manager didupdatelocations:(nsarray *)locations { self.lastlocation = locations[[locations count]-1]; self.latitudelabel.text = [NSString stringwithformat:@"%f", self.lastlocation.coordinate.latitude]; self.longitudelabel.text = [NSString stringwithformat:@ %f", self.lastlocation.coordinate.longitude]; self.speedlabel.text = [NSString stringwithformat:@"%f", self.lastlocation.speed]; }

10 Handling location changes (Swift) func locationmanager(manager: CLLocationManager!, didupdatelocations locations: [AnyObject]!) { lastlocation = locations[locations.count-1] as CLLocation latitudelabel.text = NSString(format: "%f", lastlocation.coordinate.latitude) longitudelabel.text = NSString(format: "%f", lastlocation.coordinate.longitude) speedlabel.text = NSString(format: "%f", lastlocation.speed) }

11 More on Core Location O Reilly Answers: How to effectively use Core Location in your iphone app

12 Displaying map annotations Map annotations are created using classes fulfilling the MKAnnotation protocol. The class should at least implement the initwithcoordinates:title:subtitle: method. After the class is instantiated, it is added to the MKMapView using the addannotation: method.

13 Using geocoding (ObjC) Geocoding and reverse geocoding is handled by the CLGeocoder (nonatomic, strong) CLGeocoder *mygeocoder; self.mygeocoder = [[CLGeocoder alloc] init]; [self.mygeocoder geocodeaddressstring:self.addresstextfield.text completionhandler:^(nsarray *placemarks, NSError *error) { if (placemarks.count > 0 && error == nil) { CLPlacemark *firstresult = placemarks[0]; self.latitudetextfield.text = [NSString stringwithformat:@"%f", firstresult.location.coordinate.latitude]; self.longitudetextfield.text = [NSString stringwithformat:@"%f", firstresult.location.coordinate.longitude]; } }];

14 Using geocoding (Swift) var mygeocoder: CLGeocoder! mygeocoder = CLGeocoder(); mygeocoder.geocodeaddressstring(addresstextfield.text, {(placemarks: [AnyObject]!, error: NSError!) -> Void in if (placemarks.count > 0 && error == nil){ var firstresult: CLPlacemark = placemarks[0] as CLPlacemark self.latitudetextfield.text = NSString(format: "%f", firstresult.location.coordinate.latitude) self.longitudetextfield.text = NSString(format: "%f", firstresult.location.coordinate.longitude) } })

15 Motion sensing Motion sensing is handled by the Core Motion framework. ios devices can be equipped with: an accelerometer, which detects the position of the device in relation to gravity, a gyroscope, which can detect motion when the accelerometer does not detect any (e.g. when the device rotates around its vertical axis).

16 Sensor availability (ObjC) Everything is handled by the CMMotionManager (nonatomic, strong) CMMotionManager* mymotionmanager; Not all ios devices have an accelerometer and/or gyroscope, so it s a good idea to check what is available: if ([self.mymotionmanager isaccelerometeravailable]) { NSLog(@"Accelerometer available"); } if ([self.mymotionmanager isgyroavailable]) { NSLog(@"Gyroscope available"); }

17 Sensor availability (Swift) var mymotionmanager: CMMotionManager! if (mymotionmanager.accelerometeravailable){ println("accelerometer available") } if (mymotionmanager.gyroavailable){ println("gyroscope available") }

18 Reading the accelerometer (ObjC) The accelerometer can be read using the startaccelerometerupdatestoqueue:withhandler: method. [self.mymotionmanager startaccelerometerupdatestoqueue:queue withhandler:^(cmaccelerometerdata *accelerometerdata, NSError *error) { NSLog(@"X=%.04f, Y=%.04f, Z=%.04f, accelerometerdata.acceleration.x, accelerometerdata.acceleration.y, accelerometerdata.acceleration.z); }];

19 Reading the accelerometer (Swift) mymotionmanager.startaccelerometerupdatestoqueue(ns OperationQueue(), withhandler: {(accelerometerdata: CMAccelerometerData!, error: NSError!) in println(nsstring(format:"x=%.4f, Y=%.4f, Z=%.4f", accelerometerdata.acceleration.x, accelerometerdata.acceleration.y, accelerometerdata.acceleration.z)) })

20 Reading the gyroscope (ObjC) The gyroscope can be read in a similar fashion. [self.mymotionmanager startgyroupdatestoqueue:queue withhandler:^(cmgyrodata *gyrodata, NSError *error) { NSLog(@"Gyro X=%.04f, Y=%.04f, Z=%.04f, gyrodata.rotationrate.x, gyrodata.rotationrate.y, gyrodata.rotationrate.z); }];

21 Reading the gyroscope (Swift) mymotionmanager.startgyroupdatestoqueue(nsoperationqueu e(), withhandler: {(gyrodata: CMGyroData!, error: NSError!) in println(nsstring(format:"gyro X=%.4f, Y=%.4f, Z=%.4f", gyrodata.rotationrate.x, gyrodata.rotationrate.y, gyrodata.rotationrate.z)) })