iPhone: How to determine if thread is main thread? [duplicate]

This question already has answers here: Check whether or not the current thread is the main thread (13 answers) Closed 9 years ago.

How to determine if the current thread inside a method is a main thread, or just a 开发者_运维百科thread that is asynchronous and created? Does the ID tell me?

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Like this: [NSThread isMainThread]