iOS ReplayKit 开始倒计时结束自动退出弹窗

在使用Replaykit发起屏幕录制，“开始直播”倒计时结束后，系统的弹窗并未自动消失，用户需要点击一下空白区域才能开始自己的录屏操作，这个体验并不友好

只需简单两步，使系统的弹窗自动退出

1. Broadcast Upload Extension中，屏幕录制开始时，通过CFNotificationCenter告知app主程序

import ReplayKit
class SampleHandler: RPBroadcastSampleHandler {
    overrid func broadcastStarted(withSetupInfo setupInfo: [String : NSObject]?) {
        let center = CFNotificationCenterGetDarwinNotifyCenter()
        let name = CFNotificationName("broadcastStarted" as CFString)
        CFNotificationCenterPostNotification(center, name, nil, nil, true)
    }
}

2. app主程序订阅该通知

    let center = CFNotificationCenterGetDarwinNotifyCenter()
    let name = "broadcastStarted" as CFString
    CFNotificationCenterAddObserver(center, **nil**, { _, _, _, _, _ in 
    //收到屏幕录制开始通知，跳转回app主程序
    UIApplication.shared.open(URL(string: "<your app scheme>://")!, options: [:], completionHandler: nil)
    }, name, nil, .deliverImmediately)