在iOS開發(fā)中我們需要考慮應(yīng)用程序需要對應(yīng)用設(shè)備的網(wǎng)絡(luò)狀況實時偵測，一方面，讓用戶了解自己當(dāng)前的網(wǎng)絡(luò)狀態(tài) 另一方面也增強了用戶體驗，那么我們怎么實現(xiàn)呢？
[官方示例程序] https://developer.apple.com/library/ios/samplecode/Reachability/Reachability.zip

我們將Reachability.h 和 Reachability.m 加到自己的項目中
并引用 SystemConfiguration.framework

網(wǎng)絡(luò)的幾種狀態(tài)
// the network state of the device for Reachability 2.0.
typedef enum { 
NotReachable = 0, //無連接 
ReachableViaWiFi, //使用3G/GPRS網(wǎng)絡(luò)
 ReachableViaWWAN //使用WiFi網(wǎng)絡(luò)
} NetworkStatus;

其實做起來是非常簡單的我們在ViewController.m

#import "ViewController.h"
#import "Reachability.h"
@interface ViewController ()

@property (nonatomic, strong) UIAlertController *alertVC;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    // 創(chuàng)建網(wǎng)絡(luò)探測對象
    Reachability *reach = [Reachability reachabilityWithHostName:@"www.baidu.com"];
    
    // 想通知中心注冊通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(networkChange:) name:kReachabilityChangedNotification object:nil];
    
    // 開啟通知監(jiān)控
    [reach startNotifier];
    
}

// 網(wǎng)絡(luò)狀況發(fā)生改變后，執(zhí)行該方法
- (void)networkChange:(NSNotification *)noti {
    
    self.alertVC = [UIAlertController alertControllerWithTitle:@"網(wǎng)絡(luò)提示" message:@"當(dāng)前網(wǎng)絡(luò)狀況有變更" preferredStyle:UIAlertControllerStyleAlert];
    
    UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"確定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        [_alertVC dismissViewControllerAnimated:YES completion:nil];
    }];
    [_alertVC addAction:action1];
    
    
     Reachability * reach = [noti object];
    // 判斷當(dāng)前網(wǎng)絡(luò)是否可達(dá)，可達(dá)則繼續(xù)后邊的判斷：通過哪種途徑到達(dá)，不可達(dá)，直接返回，不再執(zhí)行后邊的代碼
    if ([reach isReachable]) {
        NSLog(@"網(wǎng)絡(luò)可達(dá)");
        
    } else {
        NSLog(@"網(wǎng)絡(luò)有故障");
        _alertVC.message = @"當(dāng)前網(wǎng)絡(luò)有故障";
        [self presentViewController:_alertVC animated:YES completion:nil];
        return;
    }
    
    if ([reach isReachableViaWiFi]) {
        NSLog(@"通過WIFI到達(dá)");
        _alertVC.message = @"當(dāng)前網(wǎng)絡(luò)是無線網(wǎng),為您加載高清資源";
        [self presentViewController:_alertVC animated:YES completion:nil];
        
    } else if ([reach isReachableViaWWAN]) {
        NSLog(@"通過基站到達(dá)");
        _alertVC.message = @"當(dāng)前網(wǎng)絡(luò)是流量，正在為您節(jié)省流量";
        [self presentViewController:_alertVC animated:YES completion:nil];
        
    } else {
        NSLog(@"通過其他到達(dá)");
        _alertVC.message = @"當(dāng)前使用未知網(wǎng)絡(luò)";
        [self presentViewController:_alertVC animated:YES completion:nil];
    }
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
@end