Swift Mac OS - How to play another video/change the URL of the video with AVPlayer upon a button click?

Question

I am new to swift and I am trying to make a Mac OS app that loops a video from the app's resources using AVPlayer as the background of the window once the app has been launched. When the user selects a menu item/clicks a button the background video will instantly change to a different video from the app's resources and start looping that video as the window's background.

I was able to play the first video once the app launches following this tutorial: (https://youtu.be/QgeQc587w70) and I also successfully made the video loop itself seamlessly following this post: (Looping AVPlayer seamlessly).

The problem I am now facing is changing the video to the other one once a menu item was selected/a button was clicked. The approach I was going for is to change the url and create a new AVPlayer using the new URL and affect it to the playerView.player following this post: (Swift How to update url of video in AVPlayer when clicking on a button?). However every time the menu item is selected the app crashes with the error "thread 1 exc_bad_instruction (code=exc_i386_invop subcode=0x0)". This is apparently caused by the value of playerView being nil. I don't really understand the reason for this as playerView is an AVPlayerView object that I created using the xib file and linked to the swift file by control-dragging and I couldn't seem to find another appropriate method of doing the thing I wanted to do. If you know the reason for this and the way of fixing it please provide me some help or if you know a better method of doing what I've mention above please tell me as well. Any help would be much appreciated!

My code is as follow, the line that crashes the app is at the bottom:

import Cocoa
import AppKit
import AVKit
import AVFoundation

struct videoVariables {
    static var videoName = "Test_Video" //declaring the video name as a global variable
}

    var videoIsPlaying = true
    var theURL = Bundle.main.url(forResource:videoVariables.videoName, withExtension: "mp4") //creating the video url
    var player = AVPlayer.init(url: theURL!)

class BackgroundWindow: NSWindowController {    
    @IBOutlet weak var playerView: AVPlayerView! // AVPlayerView Linked using control-drag from xib file
    @IBOutlet var mainWindow: NSWindow!
    @IBOutlet weak var TempBG: NSImageView!
    override var windowNibName : String! {
        return "BackgroundWindow"
    }


//function used for resizing the temporary background image and the playerView to the window’s size
    func resizeBG() {
        var scrn: NSScreen = NSScreen.main()!
        var rect: NSRect = scrn.frame
        var height = rect.size.height
        var width = rect.size.width
        TempBG.setFrameSize(NSSize(width: Int(width), height: Int(height)))
        TempBG.frame.origin = CGPoint(x: 0, y: 0)
        playerView!.setFrameSize(NSSize(width: Int(width), height: Int(height)))
        playerView!.frame.origin = CGPoint(x: 0, y: 0)
    }

    override func windowDidLoad() {
        super.windowDidLoad()   
        self.window?.titleVisibility = NSWindowTitleVisibility.hidden //hide window’s title
        self.window?.styleMask = NSBorderlessWindowMask //hide window’s border
        self.window?.hasShadow = false //hide window’s shadow
        self.window?.level = Int(CGWindowLevelForKey(CGWindowLevelKey.desktopWindow)) //set window’s layer as desktopWindow layer
        self.window?.center()
        self.window?.makeKeyAndOrderFront(nil)
        NSApp.activate(ignoringOtherApps: true)
        if let screen = NSScreen.main() {
            self.window?.setFrame(screen.visibleFrame, display: true, animate: false) //resizing the window to cover the whole screen
        }
        resizeBG() //resizing the temporary background image and the playerView to the window’s size
        startVideo() //start playing and loop the first video as the window’s background  
    }

//function used for starting the video again once it has been played fully
    func playerItemDidReachEnd(notification: NSNotification) {
        playerView.player?.seek(to: kCMTimeZero)
        playerView.player?.play()
    }

//function used for starting and looping the video    
    func startVideo() {
        //set the seeking time to be 2ms ahead to prevent a black screen every time the video loops
        let playAhead = CMTimeMake(2, 100); 
            //loops the video
            NotificationCenter.default.addObserver(forName: .AVPlayerItemDidPlayToEndTime, object:
                playerView.player?.currentItem, queue: nil, using: { (_) in
                    DispatchQueue.main.async {

                        self.playerView.player?.seek(to: playAhead)
                        self.playerView.player?.play()
                    }
                })

        var playerLayer: AVPlayerLayer?
        playerLayer = AVPlayerLayer(player: player)
        playerView?.player = player
        print(playerView?.player)
        playerLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
        player.play()


    }


//changing the url to the new url and create a new AVPlayer then affect it to the playerView.player once the menu item is being selected
    @IBAction func renderBG(_ sender: NSMenuItem) {
        videoVariables.videoName = "Test_Video_2"
        var theNewURL = Bundle.main.url(forResource:videoVariables.videoName, withExtension: "mp4")
        player = AVPlayer.init(url: theNewURL!)

        //!!this line crashes the app with the error "thread 1 exc_bad_instruction (code=exc_i386_invop subcode=0x0)" every time the menu item is being selected!!
        playerView.player = player       
    }

}

Additionally, the background video is not supposed to be interactive(E.g. User cannot pause/ fast-forward the video), so any issues that might be caused by user interactivity can be ignored. The purpose of the app is to play a video on the user's desktop creating the exact same effect of running the command:

"/System/Library/Frameworks/ScreenSaver.framework/Resources/ ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine -background" in terminal.

Any help would be much appreciated!

Answer 1

You don't need to create AVPlayer from url. There is AVPlayerItem class to manipulate player playback queue.

let firstAsset = AVURLAsset(url: firstVideoUrl)
let firstPlayerItem = AVPlayerItem(asset: firstAsset)

let player = AVPlayer(playerItem: firstPlayerItem)

let secondAsset = AVURLAsset(url: secondVideoUrl)    
let secondPlayerItem = AVPlayerItem(asset: secondAsset)

player.replaceCurrentItem(with: secondPlayerItem)

Docs about AVPlayerItem