How to detect if iOS devices is connected using wifi in Swift? - ios

Question

In an old, Objective-C based project I have been using the below code to detect if the iOS devices is currently connected using Wifi (not cellular).
My attempts to translate this code into Swift 5 failed due to the Objective-C pointers. Is there a clean way to use this solution in Swift?
Or are are there better ways to solve this nowerdays? I found solutions using the Reachability port to Swift or NWPathMonitor(). While they seem to work in general, these solution are used to monitor the connection state and send notifications on changes while one time checks are not (well) supported.
Event though these solution could be used to get the current connection state, this is done using delegate callback methods or closures. Thus it is not possible to use these solutions in existing code which was created to work "synchronously" (without callbacks/closures).
Is there a simply way to use localWiFiAvailable in Swift?
The code:
+ (BOOL)localWiFiAvailable {
struct ifaddrs *addresses;
struct ifaddrs *cursor;
BOOL wiFiAvailable = NO;
if (getifaddrs(&addresses) != 0) return NO;
cursor = addresses;
while (cursor != NULL) {
if ((cursor -> ifa_addr -> sa_family == AF_INET) && !(cursor -> ifa_flags & IFF_LOOPBACK)) { // Ignore the loopback address
// Check for WiFi adapter
#if TARGET_IPHONE_SIMULATOR
wiFiAvailable = true;
break;
#else
if (strcmp(cursor -> ifa_name, "en0") == 0) {
wiFiAvailable = YES;
break;
}
#endif
}
cursor = cursor -> ifa_next;
}
freeifaddrs(addresses);
return wiFiAvailable;
}
Details on why NWPathMonitor() cannot be used:
As #baronfac pointed out in his comment NWPathMonitor() can also deliver the current state, but this can only be done using its .pathUpdateHandler closure.
I am using a third-party library where I can override a souldSendData() -> Bool method. Sending the data should not be allowed on mobile connection but only on WiFi. The methodes requires an instant decision to return true or false. Waiting for the closure is thus not possible.
So, I am limited by the existing class here. Yes, connection could change any second, however this is a different problem. e.g. NWPathMonitor can be used to cancel the transfer when connection changes to mobile.
Solving this problem in Objectiv-C was no problem using the code shown above. The question is simply, if such a "direct" solution is possible in Swift as well. While using the Objectiv-C code in the Swift project would be possible I would prefer to keep the project Swift only.

Answer 1

As mentioned by Paulw11, the recommended approach is using NWPathMonitor. A common practice is the following within a UIViewController - class:
private var monitor: NWPathMonitor?
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
monitor = NWPathMonitor()
monitor?.pathUpdateHandler = { [weak self] path in
if !path.isExpensive { // this means the device is connected via WiFi
// enter your code here
}
}
let queue = DispatchQueue(label: "Monitor")
monitor?.start(queue: queue) // start to monitor the connection
}
override func viewWillDisappear(_ animated: Bool) {
monitor?.cancel() // end to monitor the connection
super.viewWillDisappear(animated)
}
EDIT:
Thanks to FLichter and Rob Napier for the clarification. Maybe it helps to use this approach:
func shouldSendData() -> Bool {
let monitor = NWPathMonitor()
return !monitor.currentPath.isExpense
}