Using CoreLocation crashes my App when moved to background

Question

I have a very simple iOS App (Swift 5 and XCode 12.3) here. It just has two buttons to start and stop a CLLocationManager. Everything seems to work fine while the App is in the foreground. The problem is I would like to continue receiving updates even if the App is not in the foreground. I activated the checkmark "Background Modes", "Location updates". But it does not work. As soon as I put the application to the background (swiping up from the bottom of my iPhone XR) it crashes with the following error:

libc++abi.dylib: terminating with uncaught exception of type std::__1::system_error: mutex lock failed: Invalid argument
terminating with uncaught exception of type std::__1::system_error: mutex lock failed: Invalid argument

I also provided the keys for "Privacy - Location Always and When In Use Usage Description" and "Privacy - Location When In Use Usage Description" in Info.plist. The code for my view controller is as follows:

import UIKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate {
    var locationManager: CLLocationManager!

    override func viewDidLoad() {
        super.viewDidLoad()
        locationManager = CLLocationManager()
        locationManager.delegate = self
        locationManager.showsBackgroundLocationIndicator = true
        locationManager.allowsBackgroundLocationUpdates = true
        locationManager.pausesLocationUpdatesAutomatically = false
        locationManager.activityType = .other
        locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
        locationManager.distanceFilter = kCLDistanceFilterNone
    }

    @IBAction func play(_ sender: UIButton) {
        locationManager.requestAlwaysAuthorization()
        self.locationManager.startUpdatingLocation()
    }

    @IBAction func stop(_ sender: UIButton) {
        locationManager.stopUpdatingLocation()
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        locations.forEach { (location) in
            print(location)
        }
        print("
")
    }
}

The stack trace looks like and reports a SIGABRT:

libsystem_kernel.dylib`__pthread_kill:
    0x1c153240c <+0>:  mov    x16, #0x148
    0x1c1532410 <+4>:  svc    #0x80
->  0x1c1532414 <+8>:  b.lo   0x1c1532434               ; <+40>
    0x1c1532418 <+12>: pacibsp 
    0x1c153241c <+16>: stp    x29, x30, [sp, #-0x10]!
    0x1c1532420 <+20>: mov    x29, sp
    0x1c1532424 <+24>: bl     0x1c150ec20               ; cerror_nocancel
    0x1c1532428 <+28>: mov    sp, x29
    0x1c153242c <+32>: ldp    x29, x30, [sp], #0x10
    0x1c1532430 <+36>: retab  
    0x1c1532434 <+40>: ret

Sometimes it also crashes with EXC_BAD_ACCESS and the following lengthy stack trace:

libobjc.A.dylib`objc_msgSend:
    0x1a85f40e0 <+0>:   cmp    x0, #0x0                  ; =0x0 
    0x1a85f40e4 <+4>:   b.le   0x1a85f41a4               ; <+196>
    0x1a85f40e8 <+8>:   ldr    x13, [x0]
    0x1a85f40ec <+12>:  and    x16, x13, #0x7ffffffffffff8
    0x1a85f40f0 <+16>:  xpacd  x16
    0x1a85f40f4 <+20>:  mov    x15, x16
->  0x1a85f40f8 <+24>:  ldr    x11, [x16, #0x10]
    0x1a85f40fc <+28>:  tbnz   w11, #0x0, 0x1a85f4158    ; <+120>
    0x1a85f4100 <+32>:  and    x10, x11, #0xffffffffffff
    0x1a85f4104 <+36>:  eor    x12, x1, x1, lsr #7
    0x1a85f4108 <+40>:  and    x12, x12, x11, lsr #48
    0x1a85f410c <+44>:  add    x13, x10, x12, lsl #4
    0x1a85f4110 <+48>:  ldp    x17, x9, [x13], #-0x10
    0x1a85f4114 <+52>:  cmp    x9, x1
    0x1a85f4118 <+56>:  b.ne   0x1a85f4128               ; <+72>
    0x1a85f411c <+60>:  eor    x10, x10, x1
    0x1a85f4120 <+64>:  eor    x10, x10, x16
    0x1a85f4124 <+68>:  brab   x17, x10
    0x1a85f4128 <+72>:  cbz    x9, 0x1a85f44e0           ; _objc_msgSend_uncached
    0x1a85f412c <+76>:  cmp    x13, x10
    0x1a85f4130 <+80>:  b.hs   0x1a85f4110               ; <+48>
    0x1a85f4134 <+84>:  add    x13, x10, x11, lsr #44
    0x1a85f4138 <+88>:  add    x12, x10, x12, lsl #4
    0x1a85f413c <+92>:  ldp    x17, x9, [x13], #-0x10
    0x1a85f4140 <+96>:  cmp    x9, x1
    0x1a85f4144 <+100>: b.eq   0x1a85f411c               ; <+60>
    0x1a85f4148 <+104>: cmp    x9, #0x0                  ; =0x0 
    0x1a85f414c <+108>: ccmp   x13, x12, #0x0, ne
    0x1a85f4150 <+112>: b.hi   0x1a85f413c               ; <+92>
    0x1a85f4154 <+116>: b      0x1a85f44e0               ; _objc_msgSend_uncached
    0x1a85f4158 <+120>: and    x10, x11, #0x7ffffffffffffe
    0x1a85f415c <+124>: autdb  x10, x16
    0x1a85f4160 <+128>: adrp   x9, 235816
    0x1a85f4164 <+132>: add    x9, x9, #0x4fa            ; =0x4fa 
    0x1a85f4168 <+136>: sub    x12, x1, x9
    0x1a85f416c <+140>: lsr    x17, x11, #55
    0x1a85f4170 <+144>: lsr    w9, w12, w17
    0x1a85f4174 <+148>: lsr    x17, x11, #60
    0x1a85f4178 <+152>: mov    x11, #0x7fff
    0x1a85f417c <+156>: lsr    x11, x11, x17
    0x1a85f4180 <+160>: and    x9, x9, x11
    0x1a85f4184 <+164>: ldr    x17, [x10, x9, lsl #3]
    0x1a85f4188 <+168>: cmp    x12, w17, uxtw
    0x1a85f418c <+172>: b.ne   0x1a85f4198               ; <+184>
    0x1a85f4190 <+176>: sub    x17, x16, x17, lsr #32
    0x1a85f4194 <+180>: br     x17
    0x1a85f4198 <+184>: ldursw x9, [x10, #-0x8]
    0x1a85f419c <+188>: add    x16, x16, x9
    0x1a85f41a0 <+192>: b      0x1a85f40f8               ; <+24>
    0x1a85f41a4 <+196>: b.eq   0x1a85f41c8               ; <+232>
    0x1a85f41a8 <+200>: and    x10, x0, #0x7
    0x1a85f41ac <+204>: asr    x11, x0, #55
    0x1a85f41b0 <+208>: cmp    x10, #0x7                 ; =0x7 
    0x1a85f41b4 <+212>: csel   x12, x11, x10, eq
    0x1a85f41b8 <+216>: adrp   x10, 319023
    0x1a85f41bc <+220>: add    x10, x10, #0x820          ; =0x820 
    0x1a85f41c0 <+224>: ldr    x16, [x10, x12, lsl #3]
    0x1a85f41c4 <+228>: b      0x1a85f40f4               ; <+20>
    0x1a85f41c8 <+232>: mov    x1, #0x0
    0x1a85f41cc <+236>: movi   d0, #0000000000000000
    0x1a85f41d0 <+240>: movi   d1, #0000000000000000
    0x1a85f41d4 <+244>: movi   d2, #0000000000000000
    0x1a85f41d8 <+248>: movi   d3, #0000000000000000
    0x1a85f41dc <+252>: ret

I have no clue what these traces mean and I did not found a conclusive explanation on the Web. Can someone provide me with some insights (or really just the most basic example of running CLLocationManager in the background? Thanks.

Using CoreLocation crashes my App when moved to background

Answers (1)

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