They will provide some code snippets and ask for output

Second round is more detailed one - They ask design pattern (Singleton, Notification, Factory, etc) - Architectures used in current project (VIPER, MVVM, MVP) - Dispatch Queues and priorities - How to select an architecture - How to use tools for debugging?

Third round was their product discussion. People from different team like QA, Server team will have a fun discussion with you and tell you about their products.

Fourth round: Some senior guy asks general opinions about - native vs hybrid platform - code review process - VIPER architecture - Explain architecture of project currently working on