学步园

// the network state of the device for Reachability 1.5.
typedef enum {
    NotReachable = 0,
    ReachableViaCarrierDataNetwork,
    ReachableViaWiFiNetwork
} NetworkStatus;

// the network state of the device for Reachability 2.0.
typedef enum {
    NotReachable = 0,
    ReachableViaWiFi,
    ReachableViaWWAN
} NetworkStatus;

Reachability *r = [Reachability reachabilityWithHostName:@“www.apple.com”];
switch ([r currentReachabilityStatus]) {
    case NotReachable:
        // 没有网络连接
        break;
    case ReachableViaWWAN:
        // 使用3G网络
        break;
    case ReachableViaWiFi:
        // 使用WiFi网络
        break;
}

// 是否wifi
+ (BOOL) IsEnableWIFI {
    return ([[Reachability reachabilityForLocalWiFi] currentReachabilityStatus] != NotReachable);
}

// 是否3G
+ (BOOL) IsEnable3G {
    return ([[Reachability reachabilityForInternetConnection] currentReachabilityStatus] != NotReachable);
}

// My.AppDelegate.h

#import "Reachability.h"

@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
    NetworkStatus remoteHostStatus;
}

@property NetworkStatus remoteHostStatus;

@end

// My.AppDelegate.m

#import "MyAppDelegate.h"

@implementation MyAppDelegate

@synthesize remoteHostStatus;

// 更新网络状态
- (void)updateStatus {
    self.remoteHostStatus = [[Reachability sharedReachability] remoteHostStatus];
}

// 通知网络状态
- (void)reachabilityChanged  NSNotification *)note {
    [self updateStatus];
    if (self.remoteHostStatus == NotReachable) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"AppName", nil) message:NSLocalizedString(@"NotReachable", nil)
        delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
        [alert show];
        [alert release];
    }
}

// 程序启动器，启动网络监视
- (void)applicationDidFinishLaunching  UIApplication *)application {

    // 设置网络检测的站点
    [[Reachability sharedReachability] setHostName:@"www.apple.com"];
    [[Reachability sharedReachability] setNetworkStatusNotificationsEnabled:YES];
    // 设置网络状态变化时的通知函数
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:)
                                                 name:@"kNetworkReachabilityChangedNotification" object:nil];
    [self updateStatus];
}

- (void)dealloc {
    // 删除通知对象
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [window release];
    [super dealloc];
}

// MyAppDelegate.h

@class Reachability;

@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
    Reachability  *hostReach;
}

@end

// MyAppDelegate.m
- (void)reachabilityChanged  NSNotification *)note {
    Reachability* curReach = [note object];
    NSParameterAssert([curReach isKindOfClass: [Reachability class]]);
    NetworkStatus status = [curReach currentReachabilityStatus];

    if (status == NotReachable) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"AppName""
                                                        message:@"NotReachable"
                                                       delegate:nil
                                              cancelButtonTitle:@"YES" otherButtonTitles:nil];
        [alert show];
        [alert release];
    }
}

- (void)applicationDidFinishLaunching:(UIApplication *)application {
    // ...

    // 监测网络情况
    [[NSNotificationCenter defaultCenter] addObserver:self
                                          selector:@selector(reachabilityChanged:)
                                          name: kReachabilityChangedNotification
                                          object: nil];
    hostReach = [[Reachability reachabilityWithHostName:@"www.google.com"] retain];
    [hostReach startNotifer];
    // ...
}