Firebase iOS SDK - Count connected users - ios

Question

I'm using the Firebase iOS SDK to build a chat system that will let my users to connect to some random "rooms" where they can chat together. Inside the room I want to display to them the total number of people connected at the moment. The problem is that I don't know how to do that count. The number of users connected should be updated on connects and disconnects of particular users. I don't know where to start and what to do.

Answer 1

This is simple :)
Whenever a user authenticates/joins a room save them to the list of active users.
Swift
let ref = Firebase(url: "<your-firebase-db>")
ref.observeAuthEventWithBlock { authData in
if authData != nil {
// 1 - Get the ref
let activeUsersRef = Firebase(url: '<your-firebase-db>/activeUsers')
// 2 - Create a unique ref
let singleUserRef = activeUsersRef.childByAutoId()
// 3 - Add them to the list of online users
singleUserRef.setValue(authData.providerData["email"])
// 4 - When they drop their connection, remove them
singleUserRef.onDisconnectRemoveValue()
}
}
Objective-C
Firebase *ref = [[Firebase alloc] initWithUrl: #"<your-firebase-db>"];
[ref observeAuthEventWithBlock: ^(FAuthData *authData) {
Firebase *activeUsersRef = [[Firebase alloc] initWithUrl: #"<your-firebase-db>/activeUsers"];
Firebase *singleUserRef = [activeUsersRef childByAutoId];
[singleUserRef setValue: #"Whatever-the-key-is"];
[singleUserRef onDisconnectRemoveValue];
}];
The snippet above will maintain a list of active users.
All you need to do now is display the count.
Swift
// Listen to the same ref as above
let activeUsersRef = Firebase(url: 'firebase-db.firebaseio.com/activeUsers')
activeUsersRef.observeEventType(.Value, withBlock: { (snapshot: FDataSnapshot!) in
var count = 0
// if the snapshot exists, get the children
if snapshot.exists() {
count = snapshot.childrenCount
}
})
Objective-C
Firebase *activeUsersRef = [[Firebase alloc] initWithUrl: #"<your-firebase-db>/activeUsers"];
[activeUsersRef observeEventType:FEventTypeValue withBlock:^(FDataSnapshot *snapshot) {
NSUInteger count = 0;
if ([snapshot exists]) {
count = snapshot.childrenCount;
}
}];