如何在 firestore objective-c 上设置/更新数据时以秒为单位获取 Firebase 服务器时间？

Question

We are facing an issue regarding timestamp while set/update data on firestore. We want actual firebase server timestamp in seconds but by using [[FIRTimestamp timestamp].seconds] gives us timestamp in second but for system date not actual server date.

So how can we get server timestamp on app while set/update data? We also use [FIRServerValue timestamp] but its gives result in dictionary format [".sv":"timestamp"] . So we tried to get seconds from this dictionary by using following way:

NSLog(@"%ld",(NSInteger)[FIRServerValue timestamp]/1000); //105827998577

But this timestamp we get is wrong.

Answer 1

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.

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: