Crashed: com.apple.main-thread in version check function-CodePudding

My app is crashing with following error. It is random error so can't catch the error during testing.

What is causing this crash and how to fix it?

Crashlytics log

Crashed: com.apple.main-thread
0  MyApp                0x177fdc closure #1 in closure #1 in AppVersionChecker.checkVersion(force:title:message:)   4307714012 (AppVersionChecker.swift:4307714012)
1  MyApp                0x3a07fc thunk for @escaping @callee_guaranteed () -> ()   4309977084 (<compiler-generated>:4309977084)
2  libdispatch.dylib              0x631a4 _dispatch_call_block_and_release   24
3  libdispatch.dylib              0x641a8 _dispatch_client_callout   16
4  libdispatch.dylib              0x454b8 _dispatch_main_queue_callback_4CF$VARIANT$armv81   908
5  CoreFoundation                 0x4d888 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__   12
6  CoreFoundation                 0xb188 __CFRunLoopRun   2528
7  CoreFoundation                 0x1de1c CFRunLoopRunSpecific   572
8  GraphicsServices               0x19a0 GSEventRunModal   160
9  UIKitCore                      0x4ec600 -[UIApplication _run]   1080
10 UIKitCore                      0x281b08 UIApplicationMain   2028
11 MyApp                0xf678 main   23 (AppDelegate.swift:23)
12 ???                            0x102b2c250 (Missing)

Code

private func checkVersion(force: Bool, title: String?, message: String?) {
    let info = Bundle.main.infoDictionary
    guard let currentVersion = info?["CFBundleShortVersionString"] as? String else {
        NSLog("Error currentVerion")
        return
    }
    
    _ = getAppInfo { (info, error) in
        
        // Compare with version on appstore
        guard let appStoreAppVersion = info?.version else {
            NSLog("Error appStoreAppVersion")
            return
        }
        
        if let error = error {
            NSLog("getAppInfo Error: \(error)")
        } else if appStoreAppVersion.compare(currentVersion, options: .numeric) == .orderedDescending {
            DispatchQueue.main.async {
                let topController: UIViewController = UIApplication.shared.keyWindow!.rootViewController!
                topController.showAppUpdateAlert(Version: (info?.version)!, Force: force, AppURL: (info?.trackViewUrl)!, title: title, message: message)
            }
        }
    }
}

CodePudding user response：

Force unwrap are a reason to crash.

let topController: UIViewController = UIApplication.shared.keyWindow!.rootViewController!

If UIApplication.shared.keyWindow is nil, it will crash.
If UIApplication.shared.keyWindow!.rootViewController! is nil, it will crash.

(info?.version)!

If (info?.version) is nil, it will crash.

(info?.trackViewUrl)!

If (info?.trackViewUrl)! is nil, it will crash.

Now, you have optional values, it means that the value can be nil, so why use optional, in first place, and force unwrap after?

Use if let, guard let or ?? providing a default value to ensure the value exists.