如何检查本地WiFi网络中的设备是否已使用其IP地址连接？

Question

I am using MMLANScanner library into my iOS application. It's showing me all the devices that are connected to my Local WiFi Router along with the devices that was previously connected to my Local WiFi Router.

How I can make decision whether the device IP that I am getting is presently connected to my Local WiFi Router?

Answer 1

You can either use the apple 'Reachability' or by using simple ping. Following are the links to both projects.

[Simple Ping] https://developer.apple.com/library/content/samplecode/SimplePing/Introduction/Intro.html#//apple_ref/doc/uid/DTS10000716-Intro-DontLinkElementID_2

[Reachability] https://developer.apple.com/library/content/samplecode/Reachability/Introduction/Intro.html

Answer 2

Using Apple's Reachability example here is some code to check the connectivity of a device.

#import "Reachability.h"

@interface ViewController : UIViewController 
{
     BOOL isInternetConnectionAvailable;
}
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
//--Reachability--
    /*
     Observe the kNetworkReachabilityChangedNotification. When that notification is posted, the method reachabilityChanged will be called.
     */
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];

    self.internetReachability = [Reachability reachabilityForInternetConnection];
    [self.internetReachability startNotifier];
    [self updateInterfaceWithReachability:self.internetReachability];
    //--+--//


}
#pragma mark Reachability
/*!
 * Called by Reachability whenever status changes.
 */
- (void) reachabilityChanged:(NSNotification *)note
{
    Reachability* curReach = [note object];
    NSParameterAssert([curReach isKindOfClass:[Reachability class]]);
    [self updateInterfaceWithReachability:curReach];
}


- (void)updateInterfaceWithReachability:(Reachability *)reachability
{

    if (reachability == self.internetReachability)
    {
        NetworkStatus netStatus = [reachability currentReachabilityStatus];
        BOOL connectionRequired = [reachability connectionRequired];
        NSString* statusString = @"";

        //
        UIAlertController * connectivityAlert = [UIAlertController alertControllerWithTitle:@"Connectivity" message:[NSString stringWithFormat:@"Status:%@",statusString] preferredStyle:UIAlertControllerStyleAlert];
        UIAlertAction * ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil];
        [connectivityAlert addAction:ok];
        //

        switch (netStatus)
        {
            case NotReachable:        {
                statusString = NSLocalizedString(@"Access Not Available", @"Text field text for access is not available");
                /*
                 Minor interface detail- connectionRequired may return YES even when the host is unreachable. We cover that up here...
                 */
                connectionRequired = NO;

                connectivityAlert.message = [NSString stringWithFormat:@"Status:%@",statusString];
                [self presentViewController:connectivityAlert animated:YES completion:nil];
                isInternetConnectionAvailable = NO;
                break;
            }

            case ReachableViaWWAN:        {
                statusString = NSLocalizedString(@"Reachable WWAN", @"");

                connectivityAlert.message = [NSString stringWithFormat:@"Status:%@",statusString];

                isInternetConnectionAvailable = YES;
                break;
            }
            case ReachableViaWiFi:        {
                statusString= NSLocalizedString(@"Reachable WiFi", @"");

                connectivityAlert.message = [NSString stringWithFormat:@"Status:%@",statusString];

                isInternetConnectionAvailable = YES;
                break;
            }
        }

        if (connectionRequired)
        {
            NSString *connectionRequiredFormatString = NSLocalizedString(@"%@, Connection Required", @"Concatenation of status string with connection requirement");
            statusString= [NSString stringWithFormat:connectionRequiredFormatString, statusString];

            connectivityAlert.message = [NSString stringWithFormat:@"Status:%@",statusString];
            isInternetConnectionAvailable = NO;
            [self presentViewController:connectivityAlert animated:YES completion:nil];
        }
    }

}
@end