在GCD中,串行队列(例如主队列)中的所有任务是否都保证在同一个线程中运行？
解决方法
对于串行队列一般,没有.从
the Concurrency Programming Guide开始：
Serial queues (also known as private dispatch queues) execute one task
at a time in the order in which they are added to the queue. The
currently executing task runs on a distinct thread (which can vary
from task to task) that is managed by the dispatch queue.
具体来说,对于主队列,是：
The main dispatch queue is a globally available serial queue that executes tasks on the application’s main thread. […] Because it runs on your application’s main thread,the main queue is often used as a key synchronization point for an application.
