Dr Alasdair Allan, Babilim Light Industries - Learning iPhone

41 Pages·2010·5.13 MB·English

An introduction to
building mapping
applications for the
iPhone and iPad
Dr Alasdair Allan, Babilim Light Industries
Wednesday, 29 September 2010
Frameworks
Both Core Location and MapKit
Core Location frameworks are available on the
iPhone and iPad. The code you’ll
see during this presentation
Map Kit would work equally well on both
platforms.
Later on I’m going to go ahead
and build a demonstration
application for the iPhone. But I
could equally well build it for the
iPad, without changing very much
code.
Wednesday, 29 September 2010
Core Location
(and the GPS)
Wednesday, 29 September 2010
The Core Location Framework is
Core Location
an abstraction layer in front of
several different methods to
find the user’s location. It can
provide the latitude, longitude
and the altitude of the device;
along with the level of accuracy
to which this is know.
•
Abstraction layer The actual method used to
determine the users location is
abstracted away from both
•
Cell towers (12km falling to 1-3km)
the user and the developer.
• The only control the developer
Skyhook wireless (approx. 100m)
has over the chosen method is
by requesting a certain level of
• accuracy, although the actual
Some users may choose to
GPS (approx. 40m)
accuracy achieved is not
explicitly disable reporting of
guaranteed.
their position. You should
therefore always check to see
whether location services are
enabled before attempting to
turn on these services.
Wednesday, 29 September 2010
Core Location
LocationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
Before the release of the 4.0 SDK the
iPhone Simulator will always report
if( locationManager.locationServicesEnabled ) {
its location as being at Lat. +37.3,
Long. -122.0), corresponding to 1
[locationManager startUpdatingLocation];
Infinite Loop, Cupertino, CA.
} else {
Now it will ask permission to get a
location from Mac OS X. However it
...
only works with WiFi. If WiFi is
turned off, an error will occur.
}
There is also an annoying bug in the
simulator which I’ll talk about later
during the live demo.
Wednesday, 29 September 2010
Distance filters
locationManager.distanceFilter = 1000; // 1km
We can filter these
location update messages
based on a distance filter.
Changes in position of less
than this amount will not
generate an update message
to the delegate.
Wednesday, 29 September 2010
Desired accuracy
locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;
We can also set a desired level
of accuracy; this will determine
the location method(s) used by
the Core Location framework to
determine the users location.
Wednesday, 29 September 2010
Delegate methods
The CLLocationManagerDelegate
protocol offers two methods,
the first is called when a
location update.
The second is called when an
error occurs.
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:
(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
If the location manager is not able to
if( newLocation != oldLocation ) {
ascertain the user’s location immediately,
...
it reports a kCLErrorLocationUnknown
}
error and keeps trying.
}
In most cases you can choose to ignore
the error and wait for a new event.
- (void)locationManager:(CLLocationManagerH o*w)meavnear gife rt hdei udsFeari dleWniitehs Eyroruorr :
(NSError *)error { application access to the location service
... the manager will report a kCLErrorDenied
} error.
Upon receiving such an error, you should
stop the location manager.
Wednesday, 29 September 2010
The Magnetometer
(The Digital Compass)
Wednesday, 29 September 2010
Combining the heading (yaw)
information returned by this
device with the roll and pitch
information returned by the
accelerometer will let you
determine the true orientation
of the iPhone in real-time.
But that’s an entirely different
webcast.
Wednesday, 29 September 2010