全局檢測網絡狀態Reachability

寫在AppDelegate 的一個網絡檢測，通過Reachability的自身狀態方法，只要網絡狀態斷開，UIalert就會提示。

網絡檢測方法，並注冊一個通知

 //網絡檢測****************
    [[NSNotificationCenter defaultCenter] addObserver:self                                          selector:@selector(reachabilityChanged:) name: kReachabilityChangedNotification                                          object: nil];
    hostReach = [[Reachability reachabilityWithHostName:@"www.baidu.com"] retain];
    [hostReach startNotifier];

- (void)reachabilityChanged:(NSNotification*)note{
    Reachability* curReach= [note object];
    NSParameterAssert([curReach isKindOfClass: [Reachability class]]);
    NetworkStatus status= [curReach currentReachabilityStatus];
    if(status == NotReachable) {
        NSUserDefaults *user = [NSUserDefaults standardUserDefaults];
        [user setBool:1 forKey:@"network"];
        UIAlertView*alert= [[UIAlertView alloc] initWithTitle:@"網絡連接被斷開"
                                                      message:nil delegate:nil
                                            cancelButtonTitle:@"確定"otherButtonTitles:nil];
        [alert show];
        [alert release];
    }
    else
    {
       
//        UIAlertView*alert= [[UIAlertView alloc] initWithTitle:@"網絡連接成功"
//                                                      message:nil delegate:nil
//                                            cancelButtonTitle:@"確定"otherButtonTitles:nil];
//        [alert show];
//        [alert release];
    }
}