Question

我是iBeacon和Swift开发的新手，我的应用程序遇到了一些问题。在下面的代码中，我试图检测iBeacon，当我检测到信标的次要值时，我将它附加到我想要播放的链接上。启动程序时出现问题。视频开始播放一秒钟，然后整个应用程序停止并出现以下错误：

由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：'应用程序试图以模态方式呈现一个活动控制器.libc ++ abi.dylib：以NSException类型的未捕获异常终止。

var captureSession: AVCaptureSession?
var videoPreviewLayer: AVCaptureVideoPreviewLayer?

var avPlayerViewController = AVPlayerViewController()
var avPlayer:AVPlayer?

let locationManager = CLLocationManager()
let region = CLBeaconRegion(proximityUUID: UUID(uuidString: "8492E75F-4FD6-469D-B132-043FE94921D8")!, identifier: "Estimotes")


   let videos = [


    19987: NSURL ( string: "http://techslides.com/demos/sample-videos/small.mp4"),


                ]



   func locationManager(_ manager: CLLocationManager, didRangeBeacons beacons: [CLBeacon], in region: CLBeaconRegion) {

    let knownBeacons = beacons.filter{ $0.proximity != CLProximity.unknown }
    if (knownBeacons.count > 0) {
        let closestBeacon = knownBeacons[0] as CLBeacon

        if let url = self.videos[closestBeacon.minor.intValue] {


            self.avPlayer = AVPlayer(url: url as! URL)
            self.avPlayerViewController.player = self.avPlayer

        }
        self.present(self.avPlayerViewController,animated: true) { () -> Void in
            self.avPlayerViewController.player?.play()
        }
    }
}

请问您如何解决该错误？

Answer 1

问题是每秒都会调用func locationManager(_ manager: CLLocationManager, didRangeBeacons beacons: [CLBeacon], in region: CLBeaconRegion) 范围的回调。因此，呈现视频播放器的代码将每秒执行一次。这可能是第一次工作，但第二次，您将收到错误，因为对self.present(...)的调用试图呈现您已经呈现的相同视图控制器。 您无法一遍又一遍地呈现相同的视图控制器。

解决方案取决于您希望如何工作。你只想让这个演示发生一次吗？如果是这样，你可以这样做：

if (knownBeacons.count > 0) {
    let closestBeacon = knownBeacons[0] as CLBeacon

    if let url = self.videos[closestBeacon.minor.intValue] {

        // only execute this code once, if avPlayer not created yet
        if self.avPlayer == nil { 
            self.avPlayer = AVPlayer(url: url as! URL)
            self.avPlayerViewController.player = self.avPlayer
            self.present(self.avPlayerViewController,animated: true) { () -> Void in
                self.avPlayerViewController.player?.play()
            }
        }
    }
}

iBeacon检测后如何播放视频？

1 个答案: