【ios开发】如何判断当前网络连接状态(网络是否正常)

转载自：http://www.yifeiyang.net/iphone-web-development-skills-of-the-article-4-make-sure-the-network-environment-3gwifi/

感觉不错。先留着。

然后将Reachability.h 和 Reachability.m 加到自己的项目中，并引用 SystemConfiguration.framework，就可以使用了。

Reachability 中定义了3种网络状态：

// the network state of the device for Reachability 1.5.typedef enum {    NotReachable = 0,  //无连接    ReachableViaCarrierDataNetwork, //使用3G/GPRS网络    ReachableViaWiFiNetwork  //使用WiFi网络} NetworkStatus;

// the network state of the device for Reachability 2.0.typedef enum {    NotReachable = 0,  //无连接    ReachableViaWiFi,  //使用3G/GPRS网络    ReachableViaWWAN  //使用WiFi网络} NetworkStatus;

 

比如检测某一特定站点的接续状况，可以使用下面的代码：

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;}

 

检测当前网络环境：

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

 

连接状态实时通知

网络连接状态的实时检查，通知在网络应用中也是十分必要的。接续状态发生变化时，需要及时地通知用户。由于Reachability1.5版与2.0版有一些变化，这里分开来说明使用方法。

Reachability 1.5

// 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];}

 

Reachability 2.0

// 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];    // ...}