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GeoFire for iOS — 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.

Integrating GeoFire with your data

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.

Example Usage

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>.

Upgrading GeoFire

Upgrading from Geofire 1.x to 2.x

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.

Upgrading from GeoFire 1.0.x to 1.1.x

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.

Downloading GeoFire for iOS

If you're using CocoaPods, add the following to your Podfile:

pod 'GeoFire', '~> 4.0'

Using GeoFire with Swift

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'

Getting Started with Firebase

GeoFire uses Firebase Realtime Database to store location data. You can sign up here for a free account.

GeoFire for iOS Quickstart

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:

  1. Key Entered: The location of a key now matches the query criteria.
  2. Key Exited: The location of a key no longer matches the query criteria.
  3. 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.

Deployment

  • git pull to update the master branch
  • tag and push the tag for this release
  • ./build.sh to build a binary
  • From your macbook that already has been granted permissions to Firebase CocoaPods, do pod trunk push
  • Update firebase-versions with the changelog for this release.
  • Add the compiled target/GeoFire.framework.zip to the release

Contributing

If 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