swift 笔记：iOS与JavaScript的交互（二）：JavaScriptCore：20。更新UI相关的操作需要放到主线程中

Posted 2021-05-19

func alert(message: String) {
  DispatchQueue.main.async(execute: {
    let ac = UIAlertController(
        title: "invokedByJavaScript", 
        message: message, 
        preferredStyle: .alert
    )
    let action = UIAlertAction(
        title: "ok", 
        style: .default
    )
    ac.addAction(action)
    self.present(ac, animated: true)
  })
}