@escaping @callee_guaranteed (@unowned )的崩溃

Question

我的用户正面临着在Firebase Crashlytics中报告的这个崩溃。我可以看到发生崩溃的类和方法，但找不出崩溃的原因。在模拟器和我拥有的真实设备上，一切都工作得很好。

我需要一些帮助来找出坠机的真正原因。这是崩溃日志。

Crashed: com.apple.main-thread
0  OK Tested                      0x1049dc4a0 closure #1 in VideoPlayerController.setProgressLabel() + 336 (VideoPlayerController.swift:336)
1  OK Tested                      0x1049da494 thunk for @escaping @callee_guaranteed (@unowned CMTime) -> () + 4308100244 (<compiler-generated>:4308100244)
2  AVFoundation                   0x1abaefd9c -[AVPeriodicTimebaseObserver _fireBlockForTime:] + 60
3  AVFoundation                   0x1abaf03a4 -[AVPeriodicTimebaseObserver _handleTimeDiscontinuity] + 164
4  AVFoundation                   0x1abaf125c __AVTimebaseObserver_timebaseNotificationCallback_block_invoke + 112
5  libdispatch.dylib              0x1a158e9a8 _dispatch_call_block_and_release + 24
6  libdispatch.dylib              0x1a158f524 _dispatch_client_callout + 16
7  libdispatch.dylib              0x1a15726fc _dispatch_main_queue_callback_4CF$VARIANT$armv81 + 860
8  CoreFoundation                 0x1a1847748 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
9  CoreFoundation                 0x1a184261c __CFRunLoopRun + 1724
10 CoreFoundation                 0x1a1841c34 CFRunLoopRunSpecific + 424
11 GraphicsServices               0x1ab98b38c GSEventRunModal + 160
12 UIKitCore                      0x1a597422c UIApplicationMain + 1932
13 OK Tested                      0x104901480 main + 21 (GoogleAds.swift:21)
14 libdyld.dylib                  0x1a16c9800 start + 4

和实际的代码。这部分代码用于设置进度滑块和标签，以指示AVPlayerItem的进度

private func setProgressLabel() {

        player.addPeriodicTimeObserver(forInterval: CMTimeMakeWithSeconds(1/30.0, preferredTimescale: Int32(NSEC_PER_SEC)), queue: DispatchQueue.main) { [unowned self] time in

//            guard let self = self else { return }

            if let playerItem = self.player.currentItem {

                let totalDuration : CMTime = playerItem.asset.duration
                let totalDurationInSeconds : Float64 = CMTimeGetSeconds(totalDuration)

                let totalDurationInString = Functions.stringFromTimeInterval(interval: totalDurationInSeconds)

                let duration : CMTime = playerItem.currentTime()
                let seconds : Float64 = CMTimeGetSeconds(duration)

                let currentDurationInString = Functions.stringFromTimeInterval(interval: seconds)

                self.progressLabel.text = "\(currentDurationInString)/\(totalDurationInString)"

                self.progressSlider.maximumValue = Float(totalDurationInSeconds)
                self.progressSlider.setValue(Float(seconds), animated: true)

                // For Analytics: video tracking
                let percentageComplete = Float(seconds / totalDurationInSeconds * 100)

                if percentageComplete.isNaN {
                    return
                }

                if Int(seconds) == 5 || Int(seconds) == 10 {
                    if Int(seconds) != self.eventSentForQuartile {
                        self.quartile = Int(seconds)
                        self.eventSentForQuartile = self.quartile
                        // send event for quartile
                        print("Send event for quartile \(self.quartile) at time \(Int(seconds))")
                        self.trackVideoOnPlay(firstPlay: false, watchDuration: "\(Int(seconds))")
                    }
                }

                if Int(seconds) == 30 && !self.isCustomEventFor30SecondsSent {
                    AppAnalytics.playVideoEvent(video: self.video)
                    self.isCustomEventFor30SecondsSent = true
                }

                if Int(percentageComplete) == 25 || Int(percentageComplete) == 50 || Int(percentageComplete) == 75 || Int(percentageComplete) == 95 {
                    if Int(percentageComplete) != self.eventSentForQuartile {
                        self.quartile = Int(percentageComplete)
                        self.eventSentForQuartile = self.quartile
                        // send event for quartile
                        print("Send event for quartile \(self.quartile) at time \(Int(seconds))")
                        self.trackVideoOnPlay(firstPlay: false, watchDuration: "\(Int(seconds))")
                    }
                }
            }
        }
    }

Answer 1

不要使用非自己的自我。因为self可以为零。遵循以下代码：

private func setProgressLabel() {

        player.addPeriodicTimeObserver(forInterval: CMTimeMakeWithSeconds(1/30.0, preferredTimescale: Int32(NSEC_PER_SEC)), queue: DispatchQueue.main) { [weak self] time in

guard let self = self else { return }