通过使用swift

Question

如何通过使用swift在firebase中搜索该键来获取密钥的值。 说，具有以下结构，我想通过搜索userID3来检索userName3作为String？

users-used
    userID1 : userName1
    userID2 : userName2
    userID3 : userName3
    userID4 : userName4

Answer 1

Assuming that the 'users-used' directory is at the root of the structure you should be able to it in the following way:

Database.database().reference().child("users-used").child("userID3").observeSingleEvent(of: .value)  { (snapshot) in
        guard let username = snapshot.value as? String else {
            return
        }
        // username will be available here as a string if successful
    }

Keep in mind that everything in the closure will be run asynchronously and can return at any time