objective-c - performSelectorOnMainThread 调用何时执行？

Question

如果我在分离线程中使用 performSelectorOnMainThread 调用，主线程何时执行请求？它是在完成当前主线程操作后立即执行此操作，还是存在其他类型的层次结构来确定何时执行 performSelectorOnMainThread 调用？

Answer 1

它在主线程运行循环的下一次迭代时在主线程上执行。

引用 Apple 的文档:

This method queues the message on the run loop of the main thread using the default run loop modes—that is, the modes associated with the NSRunLoopCommonModes constant. As part of its normal run loop processing, the main thread dequeues the message (assuming it is running in one of the default run loop modes) and invokes the desired method.