Delete a specific value in an array from Firestore Swift

Question

I have this code here and I want to delete certain value inside the array "Answered". Is there a simple way to access the first value in the array? This is right but shows what I want to happen "Answered[0]" <- I want to get the first value in that array and delete it. Thank you in Advance

let uid = Auth.auth().currentUser?.uid
            print(self.randomArray)
          let wash = db.collection("users").document(uid!)
          wash.updateData([
            "Answered": FieldValue.arrayUnion([self.randomArray])
              ])
          }
            if(self.check.isEmpty != true){
                self.whichQuestion = self.check[0]
                self.whichQuestionString = String(self.whichQuestion)
                db.collection("users").document(uid!).updateData([
                    "Answered": FieldValue.delete(),
                ]) { err in
                    if let err = err {
                        print("Error updating document: \(err)")
                    } else {
                        print("Document successfully updated")
                    }
                }

Frank van Puffelen · Accepted Answer · 2020-04-11 14:01:34Z

2

If your array contains unique values however, you can remove the item with:

self.whichQuestionString = String(self.whichQuestion)
db.collection("users").document(uid!).updateData([
    "regions": FieldValue.arrayRemove([whichQuestionString])
])

If you only know the index of the item, there is no way to remove it without knowing the entire array.

The recipe for this is:

Read the document from Firestore
Modify the array in your application code
Write the entire modified array back to Firestore

Also see (none of which unfortunately are for Swift):

edited Apr 11, 2020 at 14:01

answered Apr 11, 2020 at 13:54

Frank van Puffelen

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1 Comment

Captain Dilan Over a year ago

Thank you very much, it worked with a little adjustment. I needed to just use "self.whichQuestion" instead of "whichQuestionString" in the ArrayRemove.

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