使用DispatchGroup，DispatchQueue和DispatchSemaphore按顺序执行带有for循环的Swift 4异步调用

I want to run a for loop in swift in order, DispatchGroup will fire them together, so I want to use DispatchQueue and DispatchSemaphore to achieve my goal. I failed to make my program work, how can I force them to wait and run one by one?, Dis