How to refactor duplicate Firestore document IDs in Swift? - ios

Question

I'm doing my very first IOS app using Cloud Firestore and have to make the same queries to my database repeatedly. I would like to get rid of the duplicate lines of code. This is examples of func where documents ID are duplicated. Also I using other queries as .delete(), .addSnapshotListener(), .setData(). Should I refactor all that queries somehow or leave them because they were used just for one time?
#objc func updateUI() {
inputTranslate.text = ""
inputTranslate.backgroundColor = UIColor.clear
let user = Auth.auth().currentUser?.email
let docRef = db.collection(K.FStore.collectionName).document(user!)
docRef.getDocument { [self] (document, error) in
if let document = document, document.exists {
let document = document
let label = document.data()?.keys.randomElement()!
self.someNewWord.text = label
// Fit the label into screen
self.someNewWord.adjustsFontSizeToFitWidth = true
self.checkButton.isHidden = false
self.inputTranslate.isHidden = false
self.deleteBtn.isHidden = false
} else {
self.checkButton.isHidden = true
self.inputTranslate.isHidden = true
self.deleteBtn.isHidden = true
self.someNewWord.adjustsFontSizeToFitWidth = true
self.someNewWord.text = "Add your first word to translate"
updateUI()
}
}
}
#IBAction func checkButton(_ sender: UIButton) {
let user = Auth.auth().currentUser?.email
let docRef = db.collection(K.FStore.collectionName).document(user!)
docRef.getDocument { (document, error) in
let document = document
let label = self.someNewWord.text!
let currentTranslate = document!.get(label) as? String
let translateField = self.inputTranslate.text!.lowercased().trimmingCharacters(in: .whitespaces)
if translateField == currentTranslate {
self.inputTranslate.backgroundColor = UIColor.green
DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) { [self] in
self.inputTranslate.backgroundColor = UIColor.clear
updateUI()}
} else {
self.inputTranslate.backgroundColor = UIColor.red
self.inputTranslate.shakingAndRedBg()
DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) { [self] in
self.inputTranslate.backgroundColor = UIColor.clear
self.inputTranslate.text = ""
}
}
}
}
func deletCurrentWord () {
let user = Auth.auth().currentUser?.email
let docRef = db.collection(K.FStore.collectionName).document(user!)
docRef.getDocument { (document, err) in
let document = document
if let err = err {
print("Error getting documents: \(err)")
} else {
let array = document!.data()
let counter = array!.count
if counter == 1 {
// The whole document will deleted together with a last word in list.
let user = Auth.auth().currentUser?.email
self.db.collection(K.FStore.collectionName).document(user!).delete() { err in
if let err = err {
print("Error removing document: \(err)")
} else {
self.updateUI()
}
}
} else {
// A current word will be deleted
let user = Auth.auth().currentUser?.email
let wordForDelete = self.someNewWord.text!
self.db.collection(K.FStore.collectionName).document(user!).updateData([
wordForDelete: FieldValue.delete()
]) { err in
if let err = err {
print("Error updating document: \(err)")
} else {
self.updateUI()
}
}
}
}
}
}
Another query example
func loadMessages() {
let user = Auth.auth().currentUser?.email
let docRef = db.collection(K.FStore.collectionName).document(user!)
docRef.addSnapshotListener { (querySnapshot, error) in
self.messages = []
if let e = error {
print(e)
} else {
if let snapshotDocuments = querySnapshot?.data(){
for item in snapshotDocuments {
if let key = item.key as? String, let translate = item.value as? String {
let newMessage = Message(key: key, value: translate)
self.messages.append(newMessage)
}
}
DispatchQueue.main.async {
self.messages.sort(by: {$0.value > $1.value})
self.secondTableView.reloadData()
let indexPath = IndexPath(row: self.messages.count - 1, section: 0)
self.secondTableView.scrollToRow(at: indexPath, at: .top, animated: false)
}
}
}
}
}
}

Answer 1

enum Error {
case invalidUser
case noDocumentFound
}
func fetchDocument(onError: #escaping (Error) -> (), completion: #escaping (FIRQueryDocument) -> ()) {
guard let user = Auth.auth().currentUser?.email else {
onError(.invalidUser)
return
}
db.collection(K.FStore.collectionName).document(user).getDocument { (document, error) in
if let error = error {
onError(.noDocumentFound)
} else {
completion(document)
}
}
}
func updateUI() {
fetchDocument { [weak self] error in
self?.hideShowViews(shouldHide: true, newWordText: nil)
} completion: { [weak self] document in
guard document.exists else {
self?.hideShowViews(shouldHide: true, newWordText: nil)
return
}
self?.hideShowViews(shouldHide: false, newWordText: document.data()?.keys.randomElement())
}
}
private func hideShowViews(shouldHide: Bool, newWordText: String?) {
checkButton.isHidden = shouldHide
inputTranslate.isHidden = shouldHide
deleteBtn.isHidden = shouldHide
someNewWord.adjustsFontSizeToFitWidth = true
someNewWord.text = newWordText ?? "Add your first word to translate"
}
The updateUI method can easily be refactored using a simple guard statement and then taking out the common code into a separate function. I also used [weak self] so that no memory leaks or retain cycles occur.
Now, you can follow the similar approach for rest of the methods.
Use guard let instead of if let to avoid nesting.
Use [weak self] for async calls to avoid memory leaks.
Take out the common code into a separate method and use a Bool flag to hide/show views.
Update for step 3:
You can create methods similar to async APIs for getDocument() or delete() etc and on completion you can update UI or perform any action. You can also create a separate class and move the fetchDocument() and other similar methods in there and use them.