ios - Crash with "function signature specialization <Arg[0] = Dead>"

Question

I cannot get my head around the crash I've received. In particular I'd be interested to find out what does <Arg[0] = Dead> mean? Is the sender in didUpdate() somehow dead?

This is the report:

Hardware Model:      iPhone11,2
Code Type:       arm64
Parent Process:   [1]

Date/Time:       2021-01-23T06:20:16.999Z
Launch Time:     2021-01-22T18:46:28Z
OS Version:      iPhone OS 14.3 (18C66)

Exception Type:  SIGTRAP
Exception Codes: TRAP_BRKPT at 0x100361d60
Crashed Thread:  0

Thread 0 Crashed:
0   App-Name                0x0000000100361d60 function signature specialization <Arg[0] = Dead> of App_Name.SessionViewController.didUpdate(_: App_Name.ElapsedTimeSource, interval: Swift.Double) -> () (SessionViewController.swift:0)
1   App-Name                0x000000010065953c App_Name.ElapsedTimeSource.(update in _B9C509359F1F9AD84C977E95030096FE)() -> () (ElapsedTimeSource.swift:57)
2   App-Name                0x00000001006593d4 App_Name.ElapsedTimeSource.start() -> () (ElapsedTimeSource.swift:48)
3   App-Name                0x000000010036111c App_Name.SessionViewController.(displayInSession in _1C441B89ACF9824195FFFFDA0A95A40F)(App_Name.Session) -> () (SessionViewController.swift:112)

The ElapsedTimeSource and the delegate in full:

protocol ElapsedTimeSourceDelegate: AnyObject {
    
    func didUpdate(_ sender: ElapsedTimeSource, interval: TimeInterval)
}

// Use on the main thread
class ElapsedTimeSource {
    
    var startDate: Date {
        didSet {
            if startDate != oldValue {
                elapsed = Date().timeIntervalSince(startDate)
            }
        }
    }
    
    weak private var delegate: ElapsedTimeSourceDelegate?
    
    private var elapsed: TimeInterval = 0
    private var isRunning = false
    private let interval: TimeInterval
    
    init(startDate: Date, delegate: ElapsedTimeSourceDelegate, interval: TimeInterval = 1) {
        self.startDate = startDate
        self.delegate = delegate
        self.interval = interval
    }
    
    func start() {
        
        if isRunning { return }
        isRunning = true
        
        elapsed = Date().timeIntervalSince(startDate)
        update() // *** Line 48 ***
    }
    
    func stop() {
        isRunning = false
    }
    
    private func update() {
        
        delegate?.didUpdate(self, interval: elapsed) // *** Line 57 ***
        
        let actualElapsed = Date().timeIntervalSince(startDate)
        let correction = elapsed - actualElapsed
                
        DispatchQueue.main.asyncAfter(deadline: .now() + interval + correction) { [weak self] in
            
            guard let self = self else { return }
            
            self.elapsed += self.interval
            
            if self.isRunning {
                self.update()
            }
        }
    }
}

And the relevant bits of the SessionViewController:

class SessionViewController: UIViewController {

    private var elapsedTimeSource: ElapsedTimeSource?

    private func displayInSession(_ session: Session) {
        if let elapsedTimeSource = elapsedTimeSource {
            elapsedTimeSource.startDate = session.startTime
            elapsedTimeSource.start()
        } else {
            elapsedTimeSource = ElapsedTimeSource(startDate: session.startTime, delegate: self)
            elapsedTimeSource?.start() // *** Line 112 ***
        }
   }
}

extension SessionViewController: ElapsedTimeSourceDelegate {
    func didUpdate(_ sender: ElapsedTimeSource, interval: TimeInterval) {
        let formatter = DateComponentsFormatter()
        if interval < 3600 {
            // Force showing minutes even when time is less than 1 min
            formatter.allowedUnits = [.second, .minute]
        } else {
            formatter.allowedUnits = [.second, .minute, .hour]
        }
        formatter.zeroFormattingBehavior = .pad

        let elapsed = formatter.string(from: interval) ?? ""
        sessionElapsedTimeLabel.text = elapsed
    }
}

I would be grateful for any learned input really!

question from:https://stackoverflow.com/questions/65858071/crash-with-function-signature-specialization-arg0-dead

Answer 1

Waitting for answers