How to read the data type Dictionary to type [String]?

Question

Here is my data structure:

The problem is I don't know how to snap back the Data which is also the Key properly. What I want is only the Key and the value "true" are only markers. And I don't even know what type of data I am currently stored and how to snap the key value back.

What I want this that:

["BAFS", "Econ", "Geog"]

The following is how I write the data:

var subjectvalue: [String] = []
let structure = subjectvalue.reduce(into:[String:String](), { $0[$1] = "true"})
 let postRef = Database.database().reference().child("posts").child(id!).child("posts").setValue(structure)

I had been stocked for few days. Anyone have idea to help? Thank you in advance.

To get the keys from a dictionary, see https://stackoverflow.com/questions/26386093/array-from-dictionary-keys-in-swift — Frank van Puffelen, May 27 '19 at 14:55

score 0 · Answer 1 · answered May 27 '19 at 15:23

You can get the dictionary from the DataSnapshot. Then get .keys of the dictionary and remove all elements which are not "true"

let postRef = Database.database().reference().child("posts").child("id").child("posts")
postRef.observe(.value) { snapshot in
    if let dict = snapshot.value as? [String : String] {
        let result = Array(dict.keys).removeAll(where: { $0 != "true" })
        print(result)
    }
}

How to read the data type Dictionary to type [String]?

1 Answers1