ios - Retrieving Data using Firebase Swift -

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i'm using firebase swift ios application. found retrieving data tutorial on firebase's guide bit confusing , not sure why when try access existing values in database results in nil values.

this have far: 

usersref.queryorderedbychild("fbid").queryequaltovalue(userid).observesingleeventoftype(.value, withblock:{ snapshot in                         print("snapshot: ",snapshot.value)

here result of printing snapshot.

snapshot:  {     1 = {         fbid = 1;         firstname = michelle;         friendlist =         {             9 = "kevin c";         };         lastname = c;         profilepicurl = "https:;         uid = "facebook:1";     }; }

however, line below results in:
fatal error: unexpectedly found nil while unwrapping optional value

 firstname = snapshot.value.objectforkey("firstname") as! string

i retrieve values user (firstname, profilepicurl, friendlist, etc) , store them in variables. seems simple perhaps i'm missing something. appreciated.

your fdatasnapshot not contain child firstname. contains child 1.

this because you're performing query , asking value. since query can have many results, returns list of results. when there's 1 result, still list of 1.

the solution loop on children:

usersref.queryorderedbychild("fbid")         .queryequaltovalue(userid)         .observesingleeventoftype(.value, withblock:{ snapshot in             child in snapshot.children {                 print("loading group \(child.key!)")              } })

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