One of the important tools that every developer under IOS should know is multithreading.
In some situations, you need to split your code execution into different threads, for example, if you want to load an image and at the same time figure something out, it’s better to use multithreading to perform two tasks simultaneously without overloading the process.
Multithreading for another can be explained by queues, as in real life people line up in the queue in stores, and in programming some of the code can be lined up.
Queues are serial and concurrent, and functions are placed in these queues synchronously (sync) or asynchronously (async).

Development GameDev Programming

Programming Swift Help tutorial RabbiFox