如果你想在iOS程序中提供一仅在wifi网络下使用(Reeder)，或者在没有网络状态下提供离线模式(Evernote)。那么你会使用到Reachability来实现网络检测。

 

写本文的目的

• 了解Reachability都能做什么
• 检测3中网络环境
  • 2G/3G
  • wifi
  • 无网络
• 如何使用通知
  • 单个controller
  • 多个controller
• 简单的功能:
  • 仅在wifi下使用

Reachability简介

Reachablity 是一个iOS下检测,iOS设备网络环境用的库。

• 监视目标网络是否可用
• 监视当前网络的连接方式
• 监测连接方式的变更

苹果官方提供的Doc

 

Github上的文档

 

安装

1. 创建 工程（network是我创建的demo工程，附件中可以下载到）
2.  使用
3. 在项目中添加 SystemConfiguration.framework 库

由于Reachability非常常用。直接将其加入到Supporting Files/networ-Prefix.pch中:

 

#import <Reachability/Reachability.h>

#import 
    

 

 如果你还不知道cocoaspod是什么,看这里:

 

使用

stackoverflow上有一篇回答，很好的解释了reachability的用法

• 一般情况一个Reachability实例就ok了。
• 一个Controller只需要一个Reachability

Block方式使用

 

- (void)viewDidLoad
{
    [super viewDidLoad];
     DLog(@"开启 www.apple.com 的网络检测");
     Reachability* reach = [Reachability reachabilityWithHostname:@"www.apple.com"];
     DLog(@"-- current status: %@", reach.currentReachabilityString);

     // start the notifier which will cause the reachability object to retain itself!

     [[NSNotificationCenter defaultCenter] addObserver:self
                                                        selector:@selector(reachabilityChanged:)
                                                             name:kReachabilityChangedNotification
                                                          object:nil];

     reach.reachableBlock = ^(Reachability * reachability)
    {
        dispatch_async(dispatch_get_main_queue(), ^{
            self.blockLabel.text = @"网络可用";
               self.blockLabel.backgroundColor = [UIColor greenColor];
        });
    };

    reach.unreachableBlock = ^(Reachability * reachability)
    {
        dispatch_async(dispatch_get_main_queue(), ^{
            self.blockLabel.text = @"网络不可用";
               self.blockLabel.backgroundColor = [UIColor redColor];
        });
    };

     [reach startNotifier];
}

- (void)viewDidLoad{    [super viewDidLoad];     DLog(@"开启 www.apple.com 的网络检测");     Reachability* reach = [Reachability reachabilityWithHostname:@"www.apple.com"];     DLog(@"-- current status: %@", reach.currentReachabilityString);         // start the notifier which will cause the reachability object to retain itself!         [[NSNotificationCenter defaultCenter] addObserver:self                                                        selector:@selector(reachabilityChanged:)                                                             name:kReachabilityChangedNotification                                                          object:nil];         reach.reachableBlock = ^(Reachability * reachability)    {        dispatch_async(dispatch_get_main_queue(), ^{            self.blockLabel.text = @"网络可用";               self.blockLabel.backgroundColor = [UIColor greenColor];        });    };       reach.unreachableBlock = ^(Reachability * reachability)    {        dispatch_async(dispatch_get_main_queue(), ^{            self.blockLabel.text = @"网络不可用";               self.blockLabel.backgroundColor = [UIColor redColor];        });    };         [reach startNotifier];}

 

 

使用notification的方式

 

- (void)viewDidLoad
{
    [super viewDidLoad];
     DLog(@"开启 www.apple.com 的网络检测");
     Reachability* reach = [Reachability reachabilityWithHostname:@"www.apple.com"];
     DLog(@"-- current status: %@", reach.currentReachabilityString);

     // start the notifier which will cause the reachability object to retain itself!

     [[NSNotificationCenter defaultCenter] addObserver:self
                                                        selector:@selector(reachabilityChanged:)
                                                             name:kReachabilityChangedNotification
                                                          object:nil];
     [reach startNotifier];
}

- (void) reachabilityChanged: (NSNotification*)note {
     Reachability * reach = [note object];

    if(![reach isReachable])
    {
        self.notificationLabel.text = @"网络不可用";
          self.notificationLabel.backgroundColor = [UIColor redColor];
          self.wifiOnlyLabel.backgroundColor = [UIColor redColor];
          self.wwanOnlyLabel.backgroundColor = [UIColor redColor];
          return;
    }

     self.notificationLabel.text = @"网络可用";
     self.notificationLabel.backgroundColor = [UIColor greenColor];

     if (reach.isReachableViaWiFi) {
          self.wifiOnlyLabel.backgroundColor = [UIColor greenColor];
          self.wifiOnlyLabel.text = @"当前通过wifi连接";
     } else {
          self.wifiOnlyLabel.backgroundColor = [UIColor redColor];
          self.wifiOnlyLabel.text = @"wifi未开启，不能用";
     }

     if (reach.isReachableViaWWAN) {
          self.wwanOnlyLabel.backgroundColor = [UIColor greenColor];
          self.wwanOnlyLabel.text = @"当前通过2g or 3g连接";
     } else {
          self.wwanOnlyLabel.backgroundColor = [UIColor redColor];
          self.wwanOnlyLabel.text = @"2g or 3g网络未使用";
     }
}

- (void)viewDidLoad{    [super viewDidLoad];     DLog(@"开启 www.apple.com 的网络检测");     Reachability* reach = [Reachability reachabilityWithHostname:@"www.apple.com"];     DLog(@"-- current status: %@", reach.currentReachabilityString);         // start the notifier which will cause the reachability object to retain itself!         [[NSNotificationCenter defaultCenter] addObserver:self                                                        selector:@selector(reachabilityChanged:)                                                             name:kReachabilityChangedNotification                                                          object:nil];     [reach startNotifier];}- (void) reachabilityChanged: (NSNotification*)note {     Reachability * reach = [note object];       if(![reach isReachable])    {        self.notificationLabel.text = @"网络不可用";          self.notificationLabel.backgroundColor = [UIColor redColor];          self.wifiOnlyLabel.backgroundColor = [UIColor redColor];          self.wwanOnlyLabel.backgroundColor = [UIColor redColor];          return;    }            self.notificationLabel.text = @"网络可用";     self.notificationLabel.backgroundColor = [UIColor greenColor];         if (reach.isReachableViaWiFi) {          self.wifiOnlyLabel.backgroundColor = [UIColor greenColor];          self.wifiOnlyLabel.text = @"当前通过wifi连接";     } else {          self.wifiOnlyLabel.backgroundColor = [UIColor redColor];          self.wifiOnlyLabel.text = @"wifi未开启，不能用";     }         if (reach.isReachableViaWWAN) {          self.wwanOnlyLabel.backgroundColor = [UIColor greenColor];          self.wwanOnlyLabel.text = @"当前通过2g or 3g连接";     } else {          self.wwanOnlyLabel.backgroundColor = [UIColor redColor];          self.wwanOnlyLabel.text = @"2g or 3g网络未使用";     }}

 

 

附件demo说明

开启wifi状态

 关闭wifi的状态

 

 

 

遗留问题

1. 如何在多个controller之前共用一个Reachability(附件demo中是一个controller一个Reachability实例)
2. 应该在什么使用停止Reachability的检测.