How do I repeat a Reachability test until it works

问题

I have an initial tableviewcontroller which is executing a reachability check. This is working without a problem within the viewDidLoad, however I would like to know the correct way to Retry the connection until it passes. The pertinent code in my implementation file is below, I have tried inserting [self ViewDidLoad] if the connection is down but this just sets the app into a loop (returning the connection failure NSLog message) and not showing the UIAlertView.

- (void)viewDidLoad
{
    [super viewDidLoad];

    if(![self connected])
    {
        // not connected
        NSLog(@"The internet is down");
        UIAlertView *connectionError = [[UIAlertView alloc] initWithTitle:@"Connection      Error" message:@"There is no Internet Connection" delegate:self cancelButtonTitle:@"Retry" otherButtonTitles:nil, nil];
        [connectionError show];
        [self viewDidLoad];
    } else
    {
        NSLog(@"Internet connection established");
        UIButton *btn = [UIButton buttonWithType:UIButtonTypeInfoDark];
        [btn addTarget:self action:@selector(infoButtonClicked:) forControlEvents:UIControlEventTouchUpInside];
        self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]    initWithCustomView:btn];
        [self start];
    }
}

回答1:

How should you use Reachability?

Always try your connection first.
If the request fails, Reachability will tell you why.
If the network comes up, Reachability will notify you. Retry the connection then.

In order to receive notifications, register for the notification, and start the reachability class from Apple:

@implementation AppDelegate {
    Reachability *_reachability;
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [[NSNotificationCenter defaultCenter]
     addObserver: self
     selector: @selector(reachabilityChanged:)
     name: kReachabilityChangedNotification
     object: nil];

    _reachability = [Reachability reachabilityWithHostName: @"www.apple.com"];
    [_reachability startNotifier];

    // ...
}

@end

To answer the notification:

- (void) reachabilityChanged: (NSNotification *)notification {
    Reachability *reach = [notification object];
    if( [reach isKindOfClass: [Reachability class]]) {
    }
    NetworkStatus status = [reach currentReachabilityStatus]; 
    NSLog(@"change to %d", status); // 0=no network, 1=wifi, 2=wan
}

If you rather use blocks instead, use KSReachability.

来源：https://stackoverflow.com/questions/15854409/how-do-i-repeat-a-reachability-test-until-it-works

标签

xcode

reachability

viewdidload