When starting the app in airplane mode, the listener is not notified

[alekop]

• I've read, understood, and done my best to follow the *CONTRIBUTING guidelines.

What did you do?

let reachability = ReachabilityNetworkManager(host: "www.apple.com")!
reachability.listener = { state in
    print("isReachable: \(state)")
}
reachability.startListening()

What did you expect to happen?

The print statement should have printed "isReachable: false"

What happened instead?

Nothing is printed when starting with no connectivity. But if you start the app with connectivity, it will print. The initial notification is not called in airplane mode.

The issue is that flags and previousFlags both have a rawValue of 0, so the guard in notifyListener returns. The previous flags should probably default unknown, rather than 0, which means not-reachable.

Alamofire Environment

Alamofire version: 4.8.0
Xcode version: 10.1
Swift version: 4.2
Platform(s) running Alamofire: iOS
macOS version running Xcode: 10.13.6

[cnoon]

Hi @alekop,

Thank you for the report. Could you report which device and version of iOS you are running? Also, could you try the following code and see if it behaves better?

let reachability = ReachabilityNetworkManager()!
reachability.listener = { print("isReachable: \($0)") }
reachability.startListening()

I tend to use the non-host specific initializer as the host version tends to be less reliable.

If you could report back on your findings I'd greatly appreciate it.

[alekop]

Hi @cnoon,

I tried the no-hostname initializer, but it didn't make any difference. The issue seems to be here, in NetworkReachabilityManager.swift:

    listenerQueue.async {
        self.previousFlags = SCNetworkReachabilityFlags()
        self.notifyListener(self.flags ?? SCNetworkReachabilityFlags())
    }

Both previousFlags, and flags get initialized to the same value, which trips the guard in notifyListener:

    func notifyListener(_ flags: SCNetworkReachabilityFlags) {
        guard previousFlags != flags else { return }
        previousFlags = flags
        
        listener?(networkReachabilityStatusForFlags(flags))
    }

[cnoon]

What versions of iOS have you tried this on @alekop? I'm guessing this is a change in functionality somewhere along the line.

[alekop]

I tried 11.4.1, 12, 12.1.

[cnoon]

Cool. Thank you for all the info here!

My guess for now is that the behavior here changed somewhere along the lines under-the-hood because I'm positive this used to work on older versions. I'll do some investigation and get a fix put together. Just FYI, I'll be out on PTO for the rest of the week so I really doubt I'll be able to get a patch put together until I get back. If this is super pressing, I'd suggest making the fix you suggested and give it a whirl in a fork. If you're confident in the change, I'd also recommend putting together a PR.

The biggest thing we'll need to investigate with making that change is that it is compatible with older versions of iOS.

[cnoon]

Okay @alekop, I just pushed up #2688 to resolve the issue you are seeing. Your breakdown of the issue was spot on and I modified the original value of previousFlags accordingly. There's a bunch more detail in #2688 specifically.

I'm going to go ahead and close this issue out. Let's continue this conversation in #2688.

Cheers. 🍻

[agnosticdev]

My guess for now is that the behavior here changed somewhere along the lines under-the-hood because I'm positive this used to work on older versions.

I'm positive this used to work. Thank you for reporting this @alekop.
I need to do some regression testing on my own projects.

[SparklingAir]

Hello! Problem is still here. I run my app from Xcode via wire on the device with turned on airplane mode and NetworkReachabilityManager()?.isReachable returns "reachable" merely once.

• Alamofire 5.6.1
• Xcode 13.2.1
• Swift 5
• iPhone 12
• iOS 15.5