Checking network status in Swift, observer does not get called - swift

Question

I have imported Reachability.h .m files like written here into my Swift project, but observer / event handler will not get called after start, why?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
NSNotificationCenter.defaultCenter().addObserver(self, selector: "reachabilityChanged:", name: kReachabilityChangedNotification, object: nil)
let hostReachability = Reachability(hostName: "www.apple.com");
hostReachability.startNotifier();
return true
}
func reachabilityChanged(note: NSNotification) { // <- DOES NOT GET CALLED
let reachability: Reachability = note.object as Reachability;
if(reachability.currentReachabilityStatus() != .NotReachable) {
}
}

Answer 1

The Reachability object returned is an autoreleased object , so it has deallocated hence notification is not triggering . You can fix by keeping a strong reference to it.
create a property to hold Reachability object
var reachability:Reachability?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
// Override point for customization after application launch.
NSNotificationCenter.defaultCenter().addObserver(self, selector: "reachabilityChanged:", name:kReachabilityChangedNotification, object: nil)
reachability = Reachability(hostName: "www.apple.com");
reachability?.startNotifier();
return true
}
This will fix your problem.
The observer's name is changed from ReachabilityChangedNotification to kReachabilityChangedNotification. Notice the "k"

Answer 2

As mentioned in other answers, you need to maintain a strong reference to the Reachability object. If you aren't checking a particular host, then call reachabilityForInternetConnection:
let internetReachability = Reachability.reachabilityForInternetConnection()
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
// Override point for customization after application launch.
NSNotificationCenter.defaultCenter().addObserver(self, selector: "reachabilityChanged:", name: kReachabilityChangedNotification, object: internetReachability)
internetReachability.startNotifier()
let hasInternet = internetReachability.currentReachabilityStatus().value == 0 ? false : true
// Save to user defaults, log to console, etc.
return true
}
func reachabilityChanged(note: NSNotification) {
var hasInternet = Bool()
if let reachability = note.object as? Reachability {
hasInternet = internetReachability.currentReachabilityStatus().value == 0 ? false : true
}
// Update user defaults, log to console, show error message, etc.
}

Answer 3

For iOS 3+, use below code:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
NotificationCenter.default.addObserver(self, selector: #selector(checkForReachability(notification:)), name: NSNotification.Name.reachabilityChanged, object: nil)
reachability = Reachability.forInternetConnection()
reachability.startNotifier()
return true
}
// MARK:
// MARK: Check Internet Status
func checkForReachability(notification:NSNotification)
{
let networkReachability = notification.object as! Reachability;
let remoteHostStatus = networkReachability.currentReachabilityStatus()
if (remoteHostStatus == NotReachable)
{
print("Not Reachable")
}
else
{
print("Reachable")
}
}