Easiest way to detect Internet connection on iOS

Question

I know this question will appear to be a dupe of many others  however  I don t feel the simple case is well explained here  Coming from an Android and BlackBerry background  making requests through HTTPUrlConnection instantly fail if there is no connection available  This seems like completely sane behavior  and I was surprised to find NSURLConnection in iOS did not emulate it   I understand that Apple  and others who have extended it  provide a Reachability class to assist with determining the network state  I was happy to first see this and fully expected to see something like bool isNetworkAvailable    but instead to my surprise I found a complex system requiring notification registrations and callbacks  and a bunch of seemingly unnecessary details  There must be a better way   My app already gracefully handles connection failures  including no connectivity  The user is notified of the failure  and the app moves on   Thus my requirements are simple  Single  synchronous function I can call before all HTTP requests to determine if I should bother actually sending the request or not  Ideally it requires no set up and just returns a boolean   Is this really not possible on iOS

User · Answer

I currently use this simple synchronous method which requires no extra files in your projects or delegates.

Import:

#import <SystemConfiguration/SCNetworkReachability.h>

Create this method:

+(bool)isNetworkAvailable
{
    SCNetworkReachabilityFlags flags;
    SCNetworkReachabilityRef address;
    address = SCNetworkReachabilityCreateWithName(NULL, "www.apple.com" );
    Boolean success = SCNetworkReachabilityGetFlags(address, &flags);
    CFRelease(address);

    bool canReach = success
                    && !(flags & kSCNetworkReachabilityFlagsConnectionRequired)
                    && (flags & kSCNetworkReachabilityFlagsReachable);

    return canReach;
}

Then, if you've put this in a MyNetworkClass:

if( [MyNetworkClass isNetworkAvailable] )
{
   // do something networky.
}

If you are testing in the simulator, turn your Mac's wifi on and off, as it appears the simulator will ignore the phone setting.

Update:

In the end I used a thread/asynchronous callback to avoid blocking the main thread; and regularly re-testing so I could use a cached result - although you should avoid keeping data connections open unnecessarily.
As @thunk described, there are better URLs to use, which Apple themselves use. http://cadinc.com/blog/why-your-apple-ios-7-device-wont-connect-to-the-wifi-network

User · Answer

It is possible and it is really simple if you look at it when finishing the implementation  which is again - very simple  since the only items you need are two boolean variables  internet reachability and host reachability  you often need more than one of these   Once you assemble your helper class that can determine the connections status  you really don t care again of the implementation needed for knowing these procedures   Example    import  lt Foundation Foundation h gt    class Reachability    interface ConnectionManager   NSObject       Reachability  internetReachable      Reachability  hostReachable      property BOOL internetActive   property BOOL hostActive   -  void  checkNetworkStatus  NSNotification   notice    end   And the  m file    import  ConnectionManager h   import  Reachability h    implementation ConnectionManager  synthesize internetActive  hostActive   - id init       self    super init       if self                 NSNotificationCenter defaultCenter  addObserver self selector  selector checkNetworkStatus   name kReachabilityChangedNotification object nil        internetReachable     Reachability reachabilityForInternetConnection  retain        internetReachable startNotifier        hostReachable     Reachability reachabilityWithHostName   www apple com   retain        hostReachable startNotifier        return self     -  void  checkNetworkStatus  NSNotification   notice       NetworkStatus internetStatus    internetReachable currentReachabilityStatus       switch  internetStatus                 case NotReachable                        NSLog   The internet is down                 self internetActive   NO               break                     case ReachableViaWiFi                        NSLog   The internet is working via WIFI                 self internetActive   YES               break                     case ReachableViaWWAN                        NSLog   The internet is working via WWAN                 self internetActive   YES               break                        NetworkStatus hostStatus    hostReachable currentReachabilityStatus       switch  hostStatus                 case NotReachable                        NSLog   A gateway to the host server is down                 self hostActive   NO               break                     case ReachableViaWiFi                        NSLog   A gateway to the host server is working via WIFI                 self hostActive   YES               break                     case ReachableViaWWAN                        NSLog   A gateway to the host server is working via WWAN                 self hostActive   YES               break                          If lower than SDK 5   Otherwise  remove the observer as pleased   -  void dealloc         NSNotificationCenter defaultCenter  removeObserver self        super dealloc       end

User · Answer

Sorry for replying too late but I hope this answer can help somebody in future   Following is a small native C code snippet that can check internet connectivity without any extra class   Add the following headers    include lt unistd h gt   include lt netdb h gt    Code   - BOOL isNetworkAvailable       char  hostname      struct hostent  hostinfo      hostname    google com       hostinfo   gethostbyname  hostname       if  hostinfo    NULL           NSLog   - gt  no connection  n            return NO            else          NSLog   - gt  connection established  n            return YES            Swift 3  func isConnectedToInternet   - gt  Bool       let hostname    google com        let hostinfo   gethostbyname hostname      let hostinfo   gethostbyname2 hostname  AF INET6   AF INET6     if hostinfo    nil           return true    internet available              return false    no internet

User · Answer

Seeing as this thread is the top google result for this type of question  I figured I would provide the solution that worked for me  I was already using AFNetworking  but searching didn t reveal how to accomplish this task with AFNetworking until midway through my project   What you want is the  AFNetworkingReachabilityManager      -- Start monitoring network reachability  globally available  --      AFNetworkReachabilityManager sharedManager  startMonitoring      AFNetworkReachabilityManager sharedManager  setReachabilityStatusChangeBlock   AFNetworkReachabilityStatus status         NSLog   Reachability changed       AFStringFromNetworkReachabilityStatus status          switch  status            case AFNetworkReachabilityStatusReachableViaWWAN          case AFNetworkReachabilityStatusReachableViaWiFi                 -- Reachable --                NSLog   Reachable                break          case AFNetworkReachabilityStatusNotReachable          default                 -- Not reachable --                NSLog   Not Reachable                break               You can also use the following to test reachability synchronously  once monitoring has started    - BOOL  isInternetReachable       return  AFNetworkReachabilityManager sharedManager  reachable

User · Answer

I extracted the code and put into one single method  hope it would help others    import  lt SystemConfiguration SystemConfiguration h gt    import  lt netinet in h gt   import  lt netinet6 in6 h gt         -  BOOL isInternetReachable           struct sockaddr in zeroAddress      bzero  amp zeroAddress  sizeof zeroAddress        zeroAddress sin len   sizeof zeroAddress       zeroAddress sin family   AF INET       SCNetworkReachabilityRef reachability   SCNetworkReachabilityCreateWithAddress kCFAllocatorDefault   const struct sockaddr   amp zeroAddress       SCNetworkReachabilityFlags flags       if reachability    NULL          return false       if    SCNetworkReachabilityGetFlags reachability   amp flags            return false       if   flags  amp  kSCNetworkReachabilityFlagsReachable     0             if target host is not reachable         return false        BOOL isReachable   false        if   flags  amp  kSCNetworkReachabilityFlagsConnectionRequired     0                   if target host is reachable and no connection is required             then we ll assume  for now  that your on Wi-Fi         isReachable   true              if     flags  amp  kSCNetworkReachabilityFlagsConnectionOnDemand      0               flags  amp  kSCNetworkReachabilityFlagsConnectionOnTraffic     0                        and the connection is on-demand  or on-traffic  if the                calling application is using the CFSocketStream or higher APIs          if   flags  amp  kSCNetworkReachabilityFlagsInterventionRequired     0                               and no  user  intervention is needed             isReachable   true                       if   flags  amp  kSCNetworkReachabilityFlagsIsWWAN     kSCNetworkReachabilityFlagsIsWWAN                       but WWAN connections are OK if the calling application                is using the CFNetwork  CFSocketStream   APIs          isReachable   true              return isReachable

User · Answer

Replacement for Apple s Reachability re-written in Swift with closures  inspired by tonymillion  https   github com ashleymills Reachability swift   Drop the file Reachability swift into your project  Alternatively   use CocoaPods or Carthage - See the Installation section of the project s README  Get notifications about network connectivity     declare this property where it won t go out of scope relative to your listener let reachability   Reachability     reachability whenReachable     reachability in     if reachability isReachableViaWiFi           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       and for stopping notifications  reachability stopNotifier

User · Answer

Checking the Internet connection availability in  iOS  Xcode 8 2   Swift 3 0  This is simple method for checking the network availability  I managed to translate it to Swift 2 0  and here the final code  The existing Apple Reachability class and other third party libraries seemed to be too complicated  to translate to Swift  This works for both 3G and WiFi connections  Don   t forget to add    SystemConfiguration framework    to your project builder     Create new swift class file Reachability in your project   import SystemConfiguration  public class Reachability   class func isConnectedToNetwork   - gt  Bool       var zeroAddress   sockaddr in       zeroAddress sin len   UInt8 MemoryLayout size ofValue  zeroAddress       zeroAddress sin family   sa family t AF INET      let defaultRouteReachability   withUnsafePointer to   amp zeroAddress             0 withMemoryRebound to  sockaddr self  capacity  1   zeroSockAddress in             SCNetworkReachabilityCreateWithAddress nil  zeroSockAddress                      var flags   SCNetworkReachabilityFlags       if  SCNetworkReachabilityGetFlags defaultRouteReachability     amp flags            return false           let isReachable    flags rawValue  amp  UInt32 kSCNetworkFlagsReachable      0     let needsConnection    flags rawValue  amp  UInt32 kSCNetworkFlagsConnectionRequired      0     return  isReachable  amp  amp   needsConnection             Check network connectivity from anywhere in project by using this code   if Reachability isConnectedToNetwork      true        print  quot Internet connection OK quot     else    print  quot Internet connection FAILED quot

User · Answer

I am writing the swift version of the accepted answer here  incase if someone finds it usefull  the code is written swift 2    You can download the required files from SampleCode  Add Reachability h and Reachability m file to your project   Now one will need to create Bridging-Header h file if none exists for your project    Inside your Bridging-Header h file add this line     import  Reachability h    Now in order to check for Internet Connection   static func isInternetAvailable   - gt  Bool       let networkReachability   Reachability   Reachability reachabilityForInternetConnection       let networkStatus   NetworkStatus   networkReachability currentReachabilityStatus        if networkStatus    NotReachable           print  No Internet           return false       else           print  Internet Available           return true

User · Answer

Someone has solved this in a simple  reusable way before  DDGReachability   EDIT  Or tonymillion Reachability

User · Answer

I think this could help      AFNetworkReachabilityManager sharedManager  startMonitoring    if  AFNetworkReachabilityManager sharedManager  isReachable        NSLog   Network reachable      else         NSLog   Network not reachable

User · Answer

I also was not happy with the Internet checking options available  Why is this not a native API        My own issue was with 100  packet loss -- when a device is connected to the router  but the router is not connected to the Internet  Reachability and others will hang for ages  I created a utility singleton class to deal with that by adding an asynch time-out  It works fine in my app  Hope it helps  Here s the link on github    https   github com fareast555 TFInternetChecker

User · Answer

EDIT  This will not work for network URLs  see comments   As of iOS 5  there is a new NSURL instance method    -  BOOL checkResourceIsReachableAndReturnError  NSError    error   Point it to the website you care about or point it to apple com  I think it is the new one-line call to see if the internet is working on your device

User · Answer

Here is a good solution for checking connectivity using Swift  without using Reachability  I found it on this blog   Create a new Swift file in your project called Network swift  for example   Paste this code inside that file   import Foundation  public class Network        class func isConnectedToNetwork  - gt Bool           var Status Bool   false         let url   NSURL string   http   google com            let request   NSMutableURLRequest URL  url           request HTTPMethod    HEAD          request cachePolicy   NSURLRequestCachePolicy ReloadIgnoringLocalAndRemoteCacheData         request timeoutInterval   10 0          var response  NSURLResponse           var data   NSURLConnection sendSynchronousRequest request  returningResponse   amp response  error  nil  as NSData           if let httpResponse   response as  NSHTTPURLResponse               if httpResponse statusCode    200                   Status   true                                  return Status           You can then check for connectivity anywhere in your project by using   if Network isConnectedToNetwork      true       println  Internet connection OK     else       println  Internet connection FAILED

User · Answer

You may also try this one if you already configured AFNetworking in your project    - void viewDidLoad      -- add connectivity notification --     NSNotificationCenter defaultCenter   addObserver self selector  selector ReachabilityDidChangeNotification   name AFNetworkingReachabilityDidChangeNotification object nil    - void ReachabilityDidChangeNotification  NSNotification   notify      -- NSLog   Reachability changed       AFStringFromNetworkReachabilityStatus status     --    NSDictionary  userInfo   notif userInfo   AFNetworkReachabilityStatus status    userInfo valueForKey AFNetworkingReachabilityNotificationStatusItem  intValue   switch  status        case AFNetworkReachabilityStatusReachableViaWWAN      case AFNetworkReachabilityStatusReachableViaWiFi             -- Reachable --       -- Do your stuff when internet connection is available --             self getLatestStuff           NSLog   Reachable            break      case AFNetworkReachabilityStatusNotReachable      default             -- Not reachable --               -- Do your stuff for internet connection not available --    NSLog   Not Reachable            break

User · Answer

Alamofire  If you are already using Alamofire for all the RESTful Api  here is what you can benifit from that   You can add following class to your app  and call MNNetworkUtils main isConnected   to get a boolean on whether its connected or not    import Alamofire  class MNNetworkUtils     static let main   MNNetworkUtils     init         manager   NetworkReachabilityManager host   google com       listenForReachability          private let manager  NetworkReachabilityManager    private var reachable  Bool   false   private func listenForReachability         self manager  listener      unowned self  status in       switch status         case  notReachable          self reachable   false       case  reachable      unknown          self reachable   true                   self manager  startListening          func isConnected   - gt  Bool       return reachable         This is a singleton class  Every time  when user connect or disconnect the network  it will override self reachable to true false correctly  because we start listening for the NetworkReachabilityManager on singleton initialization   Also in order to monitor reachability  you need to provide a host  currently I am using google com feel free to change to any other hosts or one of yours if needed

User · Answer

I did a little more research and I am updating my answer with a more current solution  I am not sure if you have already looked at it but there is a nice sample code provided by Apple     Download the sample code here    Include the Reachability h and Reachability m files in your project  Take a look at ReachabilityAppDelegate m to see an example on how to determine host reachability  reachability by WiFi  by WWAN etc  For a very simply check of network reachability  you can do something like this   Reachability  networkReachability    Reachability reachabilityForInternetConnection      NetworkStatus networkStatus    networkReachability currentReachabilityStatus       if  networkStatus    NotReachable                NSLog   There IS NO internet connection              else                NSLog   There IS internet connection                 BenjaminPiette s  Don t forget to add SystemConfiguration framework to your project

[ios] Easiest way to detect Internet connection on iOS?

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