When can I run a synchronous code by executing DispatchQueue.main.sync { }?

Question

ShinehahGnolaum OP

Created Jul ’22

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I tried running the following code and it raises the following error every time:

DispatchQueue.main.sync { }

Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)

I found this post on stackoverflow that says to never run synchronous code on the main queue:

DispatchQueue crashing with main.sync in Swift

I had assumed that because the sync { } method is there that means there is some context that it can be used. Is there absolutely no use for executing synchronous code on the main queue?

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Answer 1

Claude31 OP

Jul ’22

As explained in SO answer, context is to avoid deadlock. sync will block the main thread until it is completed, which may cause a deadlock.

Why do you want to use sync ?

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