what is typedef long dispatch_once_t in objective c [duplicate]

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• What is a typedef enum in Objective-C? 11 answers

i was going through this tutorial, and i noticed they used:

typedef long dispatch_once_t

yet they did not explain what it does. Furthermore, I have no idea what does "typedef long" mean ? i tried searching through references but didnt find an answer. Can you provide an example of how typedef long works ?

via Chebli Mohamed