關於官方Reachability Demo理解

1. 示例說明：此示例用於演示關於如何使用SystemConfiguratio Reachalility程序接口來判定相關的網絡連接狀態及狀態變化，所以在使用此示例中的Reachability.(h/m)文件於自有的項目中的前提是必須引入SystemConfiguration.framework。

2. 首選分析Reachability.h文件：

-> 首先引入<SystemConfiguration/SystemConfiguration.h>

#import <SystemConfiguration/SystemConfiguration.h>

-> 定義代表網絡狀態的枚舉類型NetworkStatus：

// 定義網絡請求可到達狀態
typedef enum 
{
    NotReachable = 0,   // 不可到達
    ReachableViaWiFi,   // 通過WiFi可到達
    ReachableViaWWAN    // 通過無線廣域網可到達(WWAN，即Wireless Wide Area Network，無線廣域網。)
} NetworkStatus;

-> 宏定義關於網絡連接變更的通知標識名稱：

#define kReachabilityChangedNotification @"kNetworkReachabilityChangedNotification"

-> 定義相關屬性：

BOOL localWiFiRef;    
// 用來保存創建測試連接返回的引用
SCNetworkReachabilityRef reachabilityRef;

 

-> 聲明各相關的方法：

// 用於檢查網絡請求是否可到達指定的主機名
+ (Reachability*) reachabilityWithHostName: (NSString*) hostName;

// 用於檢查網絡請求是否可到達指定的IP地址
+ (Reachability*) reachabilityWithAddress: (const struct sockaddr_in*) hostAddress;

// 用於檢查路由連接是否有效
+ (Reachability*) reachabilityForInternetConnection;

// 用於檢查本地的WiFi連接是否有效
+ (Reachability*) reachabilityForLocalWiFi;

// 在當前程序的運行回路中開始監聽網絡請求可到達的通知
- (BOOL) startNotifier;
- (void) stopNotifier;

// 當前網絡請求可到達狀態
- (NetworkStatus) currentReachabilityStatus;

// 當前網絡請求可到達狀態
- (NetworkStatus) currentReachabilityStatus;

// 連接需求
- (BOOL) connectionRequired;

- (void) applicationDidFinishLaunching: (UIApplication* )application 
{
    [[NSNotificationCenter defaultCenter]　　addObserver:self
　　　　　　　　　　　　　　　　　　　　　　　　　　　 selector:@selector(reachabilityChanged:)
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　name:kReachabilityChangedNotification
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　object:nil];　　
    hostReach = [[Reachability reachabilityWithHostName:@"www.apple.com"] retain];
    [hostReach startNotifier];

    internetReach = [[Reachability reachabilityForInternetConnection] retain];
    [internetReach startNotifier];
    [self updateInterfaceWithReachability:internetReach];

    wifiReach = [[Reachability reachabilityForLocalWiFi] retain];
    [wifiReach startNotifier]; 
    [self updateInterfaceWithReachability:wifiReach];

    [window makeKeyAndVisible];
}

- (void)reachabilityChanged:(NSNotification *)note
{
    Reachability *curReach = [note object];
    NSParameterAssert([curReach isKindOfClass:[Reachability class]]);
    [self updateInterfaceWithReachability:curReach];
}

- (void)updateInterfaceWithReachability:(Reachability *)curReach
{
    if (curReach == hostReach)
    {
        [self configureTextField:remoteHostStateField imageView:remoteHostIcon reachability:curReach];
        NetworkStatus netStatus = [curReach currentReachabilityStates];
        BOOL connectionRequired = [curReach connectionRequired];
        
        summaryLabel.hidden = (netStatus != ReachabilityViaWWAN);
        NSString *baseLabel = @"";
        if (connectionRequired)
        {
            baseLabel = @"Cellular data network is available.\n Internet traffic will be routed through it after a connection is established.";
        }
        else
　　　　 {
            baseLabel = @"Cellular data network is active.\n Internet traffic will be routed through it.";
        }
        summaryLabel.text = baseLabel;
    }
    if (curReach == internetReach)
    {
        [self configureTextField:internetConnectionStatusField imageView:internetConnectionIcon reachability:curReach];
    }
    if (curReach == wifiReach)
    {
        [self configureTextField:localWiFiConnectionStatusField imageView:localWiFiConnectionIcon reachability:curReach];
    }
}

- (void)configureTextField:(UITextField *)textField imageView:(UIImageView *)imageView reachability:(Reachability *)curReach
{
    NetworkStatus netStatus = [curReach currentReachabilityStatus];
    BOOL connectionRequired = [curReach connectionRequired];
    NSString *statusString = @"";
    switch (netStatus)
    {
        case NotReachable:
        {
            statusString = @"Access Not Available";
            imageView.image = [UIImage imageNamed:@"stop-32.png"];
            connectionRequired = NO;

            break;
        }
        case ReachableViaWWAN:
        {
            statusString = @"Reachable WWAN";
            imageView.image = [UIImage imageNamed:@"WWAN5.png"];
        
            break;
        }
        case ReachableViaWiFi:
        {
            statusString = @"";
            imageView.image = [UIImage imageNamed:@"Airport.png"];

            break;
        }
    }
    if (connectionRequired)
    {
        statusString = [NSString stringWithFormat:@"%@, Connection Required", statusString];
    }
    textField.text = statusString;
}

 

. 關於Reachability.m

參考此鏈接：http://blog.sina.com.cn/s/blog_65a8ab5d010110w5.html

4. 關於Reachability的使用：