GeoFire for Objective-C - Realtime location queries with Firebase
GeoFire is an open-source library for iOS that allows you to store and query a
set of keys based on their geographic location.
At its heart, GeoFire simply stores locations with string keys. Its main
benefit however, is the possibility of querying keys within a given geographic
area - all in realtime.
GeoFire uses the Firebase database for
data storage, allowing query results to be updated in realtime as they change.
GeoFire selectively loads only the data near certain locations, keeping your
applications light and responsive, even with extremely large datasets.
A compatible GeoFire client is also available for Java
and JavaScript.
GeoFire is designed as a lightweight add-on to Firebase. However, to keep things
simple, GeoFire stores data in its own format and its own location within
your Firebase database. This allows your existing data format and security rules to
remain unchanged and for you to add GeoFire as an easy solution for geo queries
without modifying your existing data.
Assume you are building an app to rate bars and you store all information for a
bar, e.g. name, business hours and price range, at /bars/<bar-id>. Later, you
want to add the possibility for users to search for bars in their vicinity. This
is where GeoFire comes in. You can store the location for each bar using
GeoFire, using the bar IDs as GeoFire keys. GeoFire then allows you to easily
query which bar IDs (the keys) are nearby. To display any additional information
about the bars, you can load the information for each bar returned by the query
at /bars/<bar-id>.
With the
expansion of Firebase at Google I/O 2016
and onwards, we’ve added a number of new features to Firebase, and have changed
initialization to incorporate them more easily. See our
setup instructions for more info
on installing and initializing the Firebase SDK.
With the release of GeoFire for iOS 1.1.0, this library now uses the new query functionality found in
Firebase 2.0.0. As a
result, you will need to upgrade to Firebase 2.x.x and add a new .indexOn rule to your Security
and Firebase Rules to get the best performance. You can view the updated rules
here
and read our docs for more information about indexing your data.
If you’re using CocoaPods, add the following
to your Podfile:
pod 'GeoFire', '~> 4.0'
GeoFire supports Swift out of the box! In order to use GeoFire and Swift from CocoaPods, add the use_frameworks! line to your Podfile, like so:
use_frameworks!
pod 'GeoFire', '~> 4.0'
GeoFire uses Firebase Realtime Database to store location data. You can sign up here for a free
account.
See the examples/SFVehicles folder for a working example of a project using GeoFire via CocoaPods.
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:
FIRDatabaseRef *geofireRef = [[FIRDatabase database] reference];
GeoFire *geoFire = [[GeoFire alloc] initWithFirebaseRef:geofireRef];
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.
In GeoFire you can set and query locations by string keys. To set a location for a key
simply call the setLocation:forKey method:
[geoFire setLocation:[[CLLocation alloc] initWithLatitude:37.7853889 longitude:-122.4056973]
forKey:@"firebase-hq"];
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:
[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!");
}
}];
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:
[geoFire removeKey:@"firebase-hq"];
geoFire.removeKey("firebase-hq")
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.
[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\"");
}
}];
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\"")
}
}
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.
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];
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)
There are three kinds of events that can occur with a geo query:
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::
FIRDatabaseHandle queryHandle = [query observeEventType:GFEventTypeKeyEntered withBlock:^(NSString *key, CLLocation *location) {
NSLog(@"Key '%@' entered the search area and is at location '%@'", key, location);
}];
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.
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:
[query observeReadyWithBlock:^{
NSLog(@"All initial data has been loaded and events have been fired!");
}];
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.
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.
git pull to update the master branch./build.sh to build a binarypod trunk pushtarget/GeoFire.framework.zip to the releaseIf you’d like to contribute to GeoFire for iOS, you’ll need to run the
following commands to get your environment set up:
$ git clone https://github.com/firebase/geofire-objc.git
$ cd geofire-objc
$ pod install
$ open Geofire.xcworkspace