How do I use FirebaseUI with multiple datasources for a tableview? - ios

Question

The documentation is sparse on FirebaseUI. How do I use different data sources for a tableview using FirebseUI?

Answer 1

For a tableview that uses a single datasource, you can use the FUIFirestoreTableViewDataSource or FirebaseTableViewDataSource. You can bind either of them to a tableview using a query (such as an FIRQuery) thus:
let query: Query = self.db.collection("users").whereField("name", isEqualTo: "Taiwo")
self.dataSource = self.tableView.bind(toFirestoreQuery: query) { tableView, indexPath, snapshot in
// get your data type out of the snapshot, create and return your cell.
}
This works very well for a tableview with a 'single source of truth' and makes your tableview react to changes etc in the database without much work from you.
However, in a case where you need to change the data on the fly (such as where you need to display different data based on user selection), using a datasource won't work. In this case, you need to use a backing collection from Firebase such as a FUIBatchedArray or FUIArray.
This isn't much different from using a Swift array alongside your tableview's datasource. The only significant difference is that you need to initialize the array using typically your viewcontroller as its delegate:
var datasourceArray = FUIBatchedArray(query: query, delegate: self)
Then
extension MyViewController: FUIBatchedArrayDelegate {
func batchedArray(_ array: FUIBatchedArray, didUpdateWith diff: FUISnapshotArrayDiff<DocumentSnapshot>) {
// you'll receive changes to your array in `diff` and `array` is a whole array with
// all new changes together with old data
datasourceArray = array
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
func batchedArray(_ array: FUIBatchedArray, willUpdateWith diff: FUISnapshotArrayDiff<DocumentSnapshot>) {
}
func batchedArray(_ array: FUIBatchedArray, queryDidFailWithError error: Error) {
}
}
Then you can use datasourceArray as you would a Swift array in your UITableViewDataSource methods:
extension MyViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return datasourceArray.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let snapshot = datasourceArray.object(at: indexPath.row)
do {
let task = try snapshot.data(as: Task.self)
// create, customise and return your cell
}
}
catch {
print("coudln't get data out of snapshot", error.localizedDescription)
}
return UITableViewCell()
}
}