Display alert if you are not connected to the internet

I believe the Swift-only solution would be the code below :

import Foundation
import SystemConfiguration

public class Reachability {

    class func isConnectedToNetwork() -> Bool {

        var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(&zeroAddress) {
            SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0)).takeRetainedValue()
        }

        var flags: SCNetworkReachabilityFlags = 0
        if SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) == 0 {
            return false
        }

        let isReachable = (flags & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags & UInt32(kSCNetworkFlagsConnectionRequired)) != 0

        return isReachable && !needsConnection
    }

}

After that, just create a method that will view the alert , if the above method returns false :

if !isConnectedToNetwork() {
    let alertController = UIAlertController(title: "Conectividade", message:
        "Você não está conectado na internet!", preferredStyle: UIAlertControllerStyle.Alert)
    alertController.addAction(UIAlertAction(title: "Fechar", style: UIAlertActionStyle.Default,handler: nil))
    self.presentViewController(alertController, animated: true, completion: nil)
}