Migration Guide from TokBox to Agora: iOS Edition

This guide provides detailed instructions for migrating from TokBox's iOS SDK to Agora's iOS SDK for voice, video, and live-broadcasting services. The primary differences between the two are in their architectures - while TokBox relies heavily on delegates, Agora uses a singleton design pattern. The guide covers how to replace TokBox's delegate design pattern with Agora's singleton design pattern, as well as how to set up local and remote video using Agora's SDK. It also explains the concept of joining a channel in Agora. The completed project can be found at https://github.com/AgoraIO-Community/Agora-iOS-SDK-Migration-from-TokBox.