Hacking with Swift - Project 9 - Grand Central Dispatch

Running complex tasks in the background with GCD.

Setup

• XCode 7.2.1
• Swift 2.0
• iOS 9.2
• iPad

Topics covered

• Using dispatch_async() to run things in the background and bringing results to the main thread.
• QoS of the different type of queues (User Interactive, User Initiated, Utility queue, Background queue). The different types of queues have an impact on the battery life.
• dispatch_async() requires code to by passed as a closure and [unowned self] must be used to prevent reference cycles (memory leaks).