The best apps don't make users wait. They dispatch tasks to the background. But processing background tasks can be tricky. What happens if the device runs out of battery? What if the network is down? Persisting to disk helps you handle such edge cases. Enter Tape, a collection of queue related classes. This talk will primarily be about it’s core component, QueueFile — a lightning fast, transactional, persistent file-based FIFO. We'll dig into it's implementation and see how it guarantees both reliability and efficiency. And you'll learn to make the most of QueueFile with real world examples.