How to check for an active Internet connection on iOS or macOS?

Important: This check should always be performed asynchronously. The majority of answers below are synchronous so be careful otherwise you’ll freeze up your app.

Swift

1) Install via CocoaPods or Carthage: https://github.com/ashleymills/Reachability.swift

2) Test reachability via closures

let reachability = Reachability()!reachability.whenReachable = { reachability in
    if reachability.connection == .wifi {
        print("Reachable via WiFi")
    } else {
        print("Reachable via Cellular")
    }
}reachability.whenUnreachable = { _ in
    print("Not reachable")
}do {
    try reachability.startNotifier()
} catch {
    print("Unable to start notifier")
}

Objective-C

1) Add SystemConfiguration framework to the project but don't worry about including it anywhere

2) Add Tony Million’s version of Reachability.h and Reachability.m to the project (found here: https://github.com/tonymillion/Reachability)

3) Update the interface section

#import "Reachability.h"// Add this to the interface in the .m file of your view controller
@interface MyViewController ()
{
    Reachability *internetReachableFoo;
}
@end

4) Then implement this method in the .m file of your view controller which you can call

// Checks if we have an internet connection or not
…