How do I get a server timestamp from Firebase's iOS API?

Question

I have an iOS app that uses Firebase and currently has a few dictionaries with keys that are NSDate objects. The obvious issue with this is that NSDate draws from the devic

Answer 1

Update: In Firebase 3.0 + Swift, you can use FIRServerValue.timestamp(). In Objective-C this is [FIRServerValue timestamp].

In Swift, you can now use FirebaseServerValue.timestamp() with Firebase 2.0.3+ (before 3.0).

The equivalent for Firebase.ServerValue.TIMESTAMP in iOS is kFirebaseServerValueTimestamp. Right now, this only works for Objective-C and not Swift.

In Swift, you can create your own global timestamp with

let kFirebaseServerValueTimestamp = [".sv":"timestamp"]

and then you'll be able to use kFirebaseServerValueTimestamp in the same way.

But you can only use this as the value or priority of a node. You won't be able to set it as the key name (although, I don't believe you could in the Web API either).

In general, calling allKeys on a dictionary does not guarantee order. But if you're using childByAutoID at a node, you can get back the right order by ordering the NSArray returned by allKeys lexicographically. Something like this would work:

[ref observeEventType:FEventTypeValue withBlock:^(FDataSnapshot *snapshot) {
    NSDictionary *value = snapshot.value;
    NSLog(@"Unsorted allKeys: %@", value.allKeys);
    NSArray *sortedAllKeys = [value.allKeys sortedArrayUsingSelector:@selector(compare:)];
    NSLog(@"Sorted allKeys: %@", sortedArray);
}];

This is similar to sorting an NSArray alphabetically, but when sorting the auto-generated IDs, you do not want localized or case insensitive sort, so you use compare: instead of localizedCaseInsensitiveCompare: