1. EEC-492/693/793 iPhone Application Development
Lecture 17
Wenbing Zhao & Nigamanth Sridhar
11/19/2018
EEC492/693/793 - iPhone Application Development

2. Outline Maps and Locations Assignment:
Build the set of apps in the handout
Note: Please do not use “Maps” as the name for the maps app if you want to test it on an i-device, because doing so would overwrite the build-in Maps app!!!
11/19/2018
11/19/2018
EEC492/693/793 - iPhone Application Development
EEC492/693/793 - iPhone Application Development 2

3. Core Location Framework
Classes
CLLocationManager
CLLocation
CLHeading
Protocol
CLLocationManagerDelegate
No UI
11/19/2018
EEC492/693/793 - iPhone Application Development

4. How to Obtain Location Information
Three tiered approach
GPS
Wifi
Cell network
11/19/2018
EEC492/693/793 - iPhone Application Development

5. EEC492/693/793 - iPhone Application Development
CLLocation
An object to represent a point and vector in the real world
@property CLLocationCoordinate2D coordinate;
@property CLLocationDistance altitude;
@property CLLocationAccuracy horizontalAccuracy;
@property CLLocationAccuracy verticalAccuracy;
@property CLLocationDirection course;
@property CLLocationSpeed speed;
- (NSDate *)timeStamp;
- (CLLocationDistance)distanceFromLocation:(CLLocation *)location
11/19/2018
EEC492/693/793 - iPhone Application Development

6. EEC492/693/793 - iPhone Application Development
CLLocationManager
Your entry point to the location service
@property CLLocation *location;
@property id <CLLocationManagerDelegate> delegate;
@property CLLocationDistance distanceFilter;
@property CLLocationAccuracy verticalAccuracy;
- (void)startUpdatingLocation
- (void)stopUpdatingLocation
- (void)startUpdatingHeading
- (void)stopUpdatingHeading
11/19/2018
EEC492/693/793 - iPhone Application Development

7. Core Location Framework: CLLocationManagerDelegate protocol
Callbacks for location change
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation;
Callbacks for heading change
didUpdateHeading:(CLHeading *)newHeading;
Error handling
didFailLoadWithError:(NSError *)error;
11/19/2018
EEC492/693/793 - iPhone Application Development

8. Getting a Location: Starting the location service
CLLocationManager* locManager =
[[CLLocationManager alloc] init];
locManager.delegate = self;
[locManager startUpdatingLocation];
11/19/2018
EEC492/693/793 - iPhone Application Development

9. Getting a Location: Using the event data
- (void)locationManager:(CLLocationManager*)manager
didUpdateToLocation:(CLLocation*)newLocation
fromLocation:(CLLocation*)oldLocation {
NSTimeInterval howRecent =
[newLocation.timestamp timeIntervalSinceNow];
if (howRecent < -10) return;
if (newLocation.horizontalAccuracy > 100) return;
// Use the coordinate data.
double lat = newLocation.coordinate.latitude;
double lon = newLocation.coordinate.longitude; }
11/19/2018
EEC492/693/793 - iPhone Application Development

10. Getting a Location: Using the event data
- (void)locationManager:(CLLocationManager *)manager
didUpdateHeading:(CLHeading *)newHeading {
// Use the coordinate data
CLLocationDirection heading = newHeading.trueHeading; }
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EEC492/693/793 - iPhone Application Development

11. Desired Accuracy: Choosing an Appropriate Accuracy Level
Choose an appropriate accuracy level
Higher accuracy impacts power consumption
Lower accuracy is “good enough” in most cases
Can change accuracy setting later if needed
Actual accuracy reported in CLLocation object
CLLocationManager* locManager = [[CLLocationManager alloc] init];
locManager.desiredAccuracy = kCLLocationAccuracyBest;
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EEC492/693/793 - iPhone Application Development

12. Distance Filter Choosing an appropriate update threshold
New events delivered when threshold exceeded
CLLocationManager* locManager = [[CLLocationManager alloc] init];
locManager.distanceFilter = 3000; // in meters
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EEC492/693/793 - iPhone Application Development

13. EEC492/693/793 - iPhone Application Development
Stopping the Service
CLLocationManager* locManager = [[CLLocationManager alloc] init];
[locManager startUpdatingLocation];
...
[locManager stopUpdatingLocation];
11/19/2018
EEC492/693/793 - iPhone Application Development

14. Responding to Errors User may deny use of the location service
Results in a kCLErrorDenied error
Protects user privacy
Occurs on a per-application basis
11/19/2018
EEC492/693/793 - iPhone Application Development

15. Responding to Errors Location may be unavailable
Results in a kCLErrorLocationUnknown error
Likely just temporary
Scan continues in background
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EEC492/693/793 - iPhone Application Development

16. EEC492/693/793 - iPhone Application Development
MapKit
API to display Maps
Classes to translate between CLLocation and human-readable addresses
Support for “annotations” (pins on a map)
Reverse Geocoding
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EEC492/693/793 - iPhone Application Development

17. EEC492/693/793 - iPhone Application Development
MKMapView
Handles display of map
“Map” & “Satellite” types
Panning and Zooming
Annotations
Display User Location
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EEC492/693/793 - iPhone Application Development

18. EEC492/693/793 - iPhone Application Development
MKMapView
Properties in MKMapView
@property MKCoordinateRegion region;
@property CLLocationCoordinate2D centerCoordinate;
@property MKMapType mapType;
@property NSArray *annotations;
@property MKUserLocation userLocation;
@property id <MKMapViewDelegate> delegate;
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EEC492/693/793 - iPhone Application Development

19. EEC492/693/793 - iPhone Application Development
MKMapViewDelegate
Callback methods about loading state:
- (void)mapViewWillStartLoadingMap:(MKMapView *)mapView;
- (void)mapViewDidFinishLoadingMap:(MKMapView *)mapView;
- (void)mapViewDidFailLoadingMap:(MKMapView *)mapView
withError:(NSError *)error;
Callback methods about region changes:
- (void)mapView:(MKMapView *)mapView
regionWillChangeAnimated:(BOOL)animated;
regionDidChangeAnimated:(BOOL)animated;
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EEC492/693/793 - iPhone Application Development

20. EEC492/693/793 - iPhone Application Development
MKMapViewDelegate
Callback methods to customize and interact with “annotations”:
// return the view for the annotation
- (MKAnnotationView *)mapView:(MKMapView *)mapView
viewForAnnotation:(id <MKAnnotation>)annotation;
// one or more annotation views were added to the map
- (void)mapView:(MKMapView *)mapView
didAddAnnotationViews:(NSArray *)views;
// the user tapped one of the annotation view’s accessory buttons
annotationView:(MKAnnotationView *)view
calloutAccessoryControlTapped:(UIControl *)control;
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EEC492/693/793 - iPhone Application Development

21. EEC492/693/793 - iPhone Application Development
Map Kit Data Types
MKCoordinateSpan: defines the area spanned by a map region
typedef struct {
CLLocationDegrees latitudeDelta;
CLLocationDegrees longitudeDelta;
} MKCoordinateSpan;
latitudeDelta
The amount of north-to-south distance (measured in degrees) to display on the map. One degree of latitude is approximately 111 kilometers (69 miles)
longitudeDelta
The amount of east-to-west distance (measured in degrees) to display for the map region. The number of kilometers spanned by a longitude range varies based on the current latitude.
For example, one degree of longitude spans a distance of approximately 111 kilometers (69 miles) at the equator but shrinks to 0 kilometers at the poles
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EEC492/693/793 - iPhone Application Development

22. EEC492/693/793 - iPhone Application Development
Map Kit Data Types
MKCoordinateRegion: defines which portion of the map to display
typedef struct {
CLLocationCoordinate2D center;
MKCoordinateSpan span;
} MKCoordinateRegion;
center
The center point of the region
span
The horizontal and vertical span representing the amount of map to display
The span also defines the current zoom level used by the map view object
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EEC492/693/793 - iPhone Application Development

23. EEC492/693/793 - iPhone Application Development
MKAnnotation
MKAnnotation is - not
Add to a MapView to plot pins
@property CLLocationCoordinate2D coordinate;
@property NSString *title;
@property NSString *subtitle;
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EEC492/693/793 - iPhone Application Development

24. EEC492/693/793 - iPhone Application Development
MKAnnotationView
View for displaying a “callout” above a map pin
-(void)initWithAnnotation:(id <MKAnnotation>)annotation reuseIdentifier:(NSString *)reuseIdentifier;
@property UIImage *image;
@property UIView *leftCalloutAccessoryView;
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EEC492/693/793 - iPhone Application Development

25. EEC492/693/793 - iPhone Application Development
MKPinAnnotationView
A subclass of MKAnnotationView
Displays a pin icon
@property BOOL animatesDrop
@property MKPinAnnotationColor pinColor
enum {
MKPinAnnotationColorRed = 0,
MKPinAnnotationColorGreen,
MKPinAnnotationColorPurple };
typedef NSUInteger MKPinAnnotationColor;
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EEC492/693/793 - iPhone Application Development

26. EEC492/693/793 - iPhone Application Development
MKPlacemark
Conforms to MKAnnotation protocol
Convenience for holding human-readable addresses alongside Coordinate
- (void)initWithCoordinate:(CLLocationCoordinate2D *)coordinate addressDictionary:(NSDictionary *)dictionary;
Easy to convert between AddressBook addresses and location:
thoroughfare, subThoroughfare, locality, subLocality, administrativeArea, subAdministrativeArea, postalCode, country, countryCode
11/19/2018
EEC492/693/793 - iPhone Application Development

27. EEC492/693/793 - iPhone Application Development
MKUserLocation
Special case of an MKAnnotation
Represents device’s location only
@property BOOL updating (getter = isUpdating);
@property CLLocation *location;
@property NSString *title;
@property NSString *subtitle;
11/19/2018
EEC492/693/793 - iPhone Application Development

28. EEC492/693/793 - iPhone Application Development
MKReverseGeocoder
Given a location, what’s the human-readable address?
- (void)initWithCoordinate:(CLLocationCoordinate2D)coordinate;
@property id <MKReverseGeocoderDelegate> delegate;
- (void)start;
- (void)cancel;
Delegate callbacks:
- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder
didFindPlacemark:(MKPlacemark *)placemark;
didFailWithError:(NSError *)error;
11/19/2018
EEC492/693/793 - iPhone Application Development