Grand Central Dispatch (GCD)

Ever used an app that froze when loading data? That's often due to blocking the main thread.

The main thread is where all UI updates and user interactions happen. If you perform a long-running task there, your app becomes unresponsive.

Concurrency means running multiple tasks seemingly at the same time. This keeps the main thread free, ensuring a smooth user experience.

Grand Central Dispatch (GCD) is Apple's powerful low-level API for managing concurrent operations. It's built on top of C and blocks, and makes it easy to perform tasks asynchronously.

GCD helps you run code concurrently by managing dispatch queues. You tell GCD what tasks to run, and it decides when and how to execute them on available processor cores.