swift use of simple GCD

Disclaimer: This article is a blogger original article, shall not be reproduced without the bloggers allowed. https://blog.csdn.net/qq_26918391/article/details/76570615

• 1. The most common template GCD

  Global asynchronous execution queue

  DispatchQueue.global().async {
  //耗时操作写在这里 
               DispatchQueue.main.async { 
                    //回到主线刷新 
               }
  }

  DispatchQueue.global().async {
  //耗时操作写在这里 
               DispatchQueue.main.sync { 
                    //回到主线刷新 
               }
  }

• 2. delay call

  let delay:TimeInterval = 3
  DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + delay) {         //3秒后在主线程执行
  }