Return Statement Error using Firebase in Swift
问题 I made a function that connects to firebase, goes to a specific path and then gives me the value. When I print(snapshot.value), it gives me the value I need. When I call the function, userProfile is empty. I need userProfile to return the snapshot String. func getUserData(uid: String) -> String{ var _REF_USERNAME = FIRDatabase.database().reference().child("users").child(uid).child("profile").child("username") var userProfile = String() _REF_USERNAME.observe(.value, with: {(snapshot) in print(