Example app to show how to build basic chat functionality.

• Cloud Firestore to store message groups / messages and handle snapshot diffs.
• Firebase Store to store images.
• Firebase Authentication to login users.
• MessageKit to render chat style UI.

• Xcode 12.3
• Swift 5.3.2
• Cocoapod 1.10.0

• Create a Firebase project in Firebase portal.
• Create an iOS App for this project.
• Download GoogleService-Info.plist from Firebase portal and add to the iOS project.
• Allow anonymous authentication in Firebase.
• Provision Cloud Firestore and Storage.

• When the app launches, user will need to login as anonymous user providing a user name. This is executed by Auth.auth().signInAnonymously(completion: nil) which creates an anonymous user.

• Create a Mesage Group by entering group name. This data is serialized and stored in Cloud Firestore. On saving, ListenerRegistration will get the snapshot changes and creates MessageGroup object and reloads tableview with new changes.

• Messages are handled the same way. Any message sent is serialized and sent to Cloud Firestore and listeners receive the snapshots and creates ChatMessage object with kind as .text(content)and reloads MessagesCollectionView.

• If the message is a picture, it is compacted and uploads to Firebase Storage and gets downloadURL. This URL along with other message properties are serialized and send to Cloud Firestore. Listeners gets the changes and downloads the image from URL and will create ChatMessage object with kind as .photo(imageMediaItem) and reloads MessagesCollectionView.