See the examples/SFVehicles folder for a working example of a project using GeoFire via CocoaPods.
GeoFire
A GeoFire object is used to read and write geo location data to your Firebase database
and to create queries. To create a new GeoFire instance you need to attach it to a Firebase database reference:
Objective-C
FIRDatabaseRef *geofireRef = [[FIRDatabase database] reference];
GeoFire *geoFire = [[GeoFire alloc] initWithFirebaseRef:geofireRef];
Swift
let geofireRef = Database.database().reference()
let geoFire = GeoFire(firebaseRef: geofireRef)
Note that you can point your reference to anywhere in your Firebase database, but don't
forget to set up security rules for
GeoFire.
Setting location data
In GeoFire you can set and query locations by string keys. To set a location for a key
simply call the setLocation:forKey method:
Objective-C
[geoFire setLocation:[[CLLocation alloc] initWithLatitude:37.7853889 longitude:-122.4056973]
forKey:@"firebase-hq"];
Swift
geoFire.setLocation(CLLocation(latitude: 37.7853889, longitude: -122.4056973), forKey: "firebase-hq")
Alternatively a callback can be passed which is called once the server
successfully saves the location:
Objective-C
[geoFire setLocation:[[CLLocation alloc] initWithLatitude:37.7853889 longitude:-122.4056973]
forKey:@"firebase-hq"
withCompletionBlock:^(NSError *error) {
if (error != nil) {
NSLog(@"An error occurred: %@", error);
} else {
NSLog(@"Saved location successfully!");
}
}];
Swift
geoFire.setLocation(CLLocation(latitude: 37.7853889, longitude: -122.4056973), forKey: "firebase-hq") { (error) in
if (error != nil) {
print("An error occured: \(error)")
} else {
print("Saved location successfully!")
}
}
To remove a location and delete the location from your database simply call:
Objective-C
[geoFire removeKey:@"firebase-hq"];
Swift
geoFire.removeKey("firebase-hq")
Retrieving a location
Retrieving locations happens with callbacks. If the key is not present in
GeoFire, the callback will be called with nil. If an error occurred, the
callback is passed the error and the location will be nil.
Objective-C
[geoFire getLocationForKey:@"firebase-hq" withCallback:^(CLLocation *location, NSError *error) {
if (error != nil) {
NSLog(@"An error occurred getting the location for \"firebase-hq\": %@", [error localizedDescription]);
} else if (location != nil) {
NSLog(@"Location for \"firebase-hq\" is [%f, %f]",
location.coordinate.latitude,
location.coordinate.longitude);
} else {
NSLog(@"GeoFire does not contain a location for \"firebase-hq\"");
}
}];
Swift
geoFire.getLocationForKey("firebase-hq") { (location, error) in
if (error != nil) {
print("An error occurred getting the location for \"firebase-hq\": \(error.localizedDescription)")
} else if (location != nil) {
print("Location for \"firebase-hq\" is [\(location.coordinate.latitude), \(location.coordinate.longitude)]")
} else {
print("GeoFire does not contain a location for \"firebase-hq\"")
}
}
Geo Queries
GeoFire allows you to query all keys within a geographic area using GFQuery
objects. As the locations for keys change, the query is updated in realtime and fires events
letting you know if any relevant keys have moved. GFQuery parameters can be updated
later to change the size and center of the queried area.
Objective-C
CLLocation *center = [[CLLocation alloc] initWithLatitude:37.7832889 longitude:-122.4056973];
// Query locations at [37.7832889, -122.4056973] with a radius of 600 meters
GFCircleQuery *circleQuery = [geoFire queryAtLocation:center withRadius:0.6];
// Query location by region
MKCoordinateSpan span = MKCoordinateSpanMake(0.001, 0.001);
MKCoordinateRegion region = MKCoordinateRegionMake(center.coordinate, span);
GFRegionQuery *regionQuery = [geoFire queryWithRegion:region];
Swift
let center = CLLocation(latitude: 37.7832889, longitude: -122.4056973)
// Query locations at [37.7832889, -122.4056973] with a radius of 600 meters
var circleQuery = geoFire.queryAtLocation(center, withRadius: 0.6)
// Query location by region
let span = MKCoordinateSpanMake(0.001, 0.001)
let region = MKCoordinateRegionMake(center.coordinate, span)
var regionQuery = geoFire.queryWithRegion(region)
Receiving events for geo queries
There are three kinds of events that can occur with a geo query:
- Key Entered: The location of a key now matches the query criteria.
- Key Exited: The location of a key no longer matches the query criteria.
- Key Moved: The location of a key changed but the location still matches the query criteria.
Key entered events will be fired for all keys initially matching the query as well as any time
afterwards that a key enters the query. Key moved and key exited events are guaranteed to be
preceded by a key entered event.
To observe events for a geo query you can register a callback with observeEventType:withBlock::
Objective-C
FIRDatabaseHandle queryHandle = [query observeEventType:GFEventTypeKeyEntered withBlock:^(NSString *key, CLLocation *location) {
NSLog(@"Key '%@' entered the search area and is at location '%@'", key, location);
}];
Swift
var queryHandle = query.observeEventType(.KeyEntered, withBlock: { (key: String!, location: CLLocation!) in
print("Key '\(key)' entered the search area and is at location '\(location)'")
})
To cancel one or all callbacks for a geo query, call
removeObserverWithFirebaseHandle: or removeAllObservers:, respectively.
Waiting for queries to be "ready"
Sometimes you want to know when the data for all the initial keys has been
loaded from the server and the corresponding events for those keys have been
fired. For example, you may want to hide a loading animation after your data has
fully loaded. GFQuery offers a method to listen for these ready events:
Objective-C
[query observeReadyWithBlock:^{
NSLog(@"All initial data has been loaded and events have been fired!");
}];
Swift
query.observeReadyWithBlock({
print("All initial data has been loaded and events have been fired!")
})
Note that locations might change while initially loading the data and key moved and key
exited events might therefore still occur before the ready event was fired.
When the query criteria is updated, the existing locations are re-queried and the
ready event is fired again once all events for the updated query have been
fired. This includes key exited events for keys that no longer match the query.
Updating the query criteria
To update the query criteria you can use the center and radius properties on
the GFQuery object. Key exited and key entered events will be fired for
keys moving in and out of the old and new search area, respectively. No key moved
events will be fired as a result of the query criteria changing; however, key moved
events might occur independently.
