xcode - 如何重复可达性测试直至其正常工作

Question

我有一个正在执行可达性检查的初始 TableView Controller 。这在 viewDidLoad 中工作没有问题，但是我想知道重试连接直到它通过的正确方法。我的实现文件中的相关代码如下，如果连接断开，我尝试插入 [self ViewDidLoad] 但这只会将应用程序设置为循环(返回连接失败 NSLog 消息)并且不显示 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];
    }
}

Answer 1

你应该如何使用Reachability ？

• 始终先尝试连接。
• 如果请求失败，Reachability 会告诉您原因。
• 如果网络可用，Reachability 会通知您。然后重试连接。

为了接收通知，请注册通知并启动 Apple 的可达性类:

@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

回复通知:

- (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
}

如果您更愿意使用 block ，请使用 KSReachability .