iOS 实时监测网络状态（通过Reachability）

在AppDelegate.m中

@property (nonatomic, strong) Reachability *reach;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    // 监测网络情况
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(reachabilityChanged:)
                                                 name: kReachabilityChangedNotification
                                               object: nil];
    Reachability *reach = [Reachability reachabilityWithHostName:@"www.apple.com"];
    [reach startNotifier];
    self.reach = reach;
}

通知触发执行的方法

#pragma mark - 网络状态变化通知
- (void)reachabilityChanged:(NSNotification*)note {
    
    Reachability* curReach = [note object];
    NSParameterAssert([curReach isKindOfClass: [Reachability class]]);
    NetworkStatus status = [curReach currentReachabilityStatus];
    
    /*
     NotReachable = 0, 无网络连接
     ReachableViaWiFi, Wifi
     ReachableViaWWAN 2G/3G/4G/5G
     */
    if (status == NotReachable) {
       
       // 没有网络的更多操作 
// 实现类似接到电话效果   self.window.frame = CGRectMake(0, 40, __width, __height-40);
        
    } else if (status == ReachableViaWiFi) {
        NSLog(@"Wifi");
    } else {
        NSLog(@"3G/4G/5G");
    }
}

- (void)dealloc {
    [_reach stopNotifier];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

完毕，亲测可用