ios网络开发 网络状态检查

网络连接中用到的类：

一.Reachability 

    1.添加 Reachability 的.h和.m文件，再添加SystemConfiguration.framework。

    2.Reachability中定义了三种网络状态：

  typedef Num{

NotReachable = 0,  //无连接

ReachableViaWiFi,  //使用3G/GPRS网络

ReachableViaWWAN   //使用WiFi网络

       }NetworkStatus;

     3.示例：

  Reachability *reachability = [Reachablity  reachabilityWithHostName:@"www.baidu.com"];

  switch([reachabilityStatus]){

case  NotReachable:

//TODO 

break; 

case  ReachableViaWiFi:

//TODO  

break; 

case  ReachableViaWWAN:

//TODO  

break;  

 } 

      4.检查当前网络环境

程序启动时，如果想检测可用的网络环境，可以像这样来使用

  //是否wifi

+ (BOOL)isEnableWIFI 

{

return ([[Reachability reachabiliyForLocalWIFI] currentReachabilityStatus] != NotReachable); 

  }

 

   //是否3G

+ (BOOL)isEnable3G

{

return ([[Reachability reachabiliyForInternetConnetion] currentReachabilityStatus] != NotReachable); 

   }

 

   示例：

- (void)viewWillAppear:(BOOL)animated

{ 

  if (([Reachability reachabiliyForInternetConnetion].currentReachabilityStatus == NotReachable) && [Reachability                         reachabiliyForLocalWIFI].currentReachabilityStatus == NotReachable))

{

self.navigationItem.hidesBackButton = YES;

[self.navigationItem setLeftBarButtonItem:nil animated:NO]; 

} 

 

 } 

 

       5.链接状态的实时通知

实时检查，持续状态发生变化时，需要及时地通知用户：

 

   Reachability  
  1.5版本 
  
 
  // 
  MyAppDelegate.h 
  
 
  
 
  #import  
  " 
  Reachability 
  " 
  
 
  
 
  @interface MyAppDelegate:NSObject<UIApplicationDelegate> 
  
{ 
  
     
  
} 
  
 
  
@property NetworkStatus remoteHostStatus; 
  
 
  
 
  @end  
 

 

 //MyAppDelegate.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) 
  
   { 
  
       UIAlert *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 
  
{ 
  
    
  // 
  设置网络监测的站点 
  
   [[Reachability sharedReachability] setHostName: 
  @" 
  www.baidu.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版本 
  
 
  // 
  MyAppDelegate.h 
  
 
  
 
  #import  
  " 
  Reachability 
  " 
  
 
  @class Reachability; 
  
 
  @interface MyAppDelegate:NSObject<UIApplicationDelegate> 
  
{ 
  
     Reachability *hostReach; 
  
} 
  
 
  
 
  
 
  @end  
  
  
  
  
  // 
  MyAppDelegate.m 
  
 
  
 
  #import  
  " 
  MyAppDelegate.h 
  " 
  
 
  
 
  @implementation MyAppDelegate 
  
 
  
 
  // 
  通知网络状态 
  
- ( 
  void)reachabilityChanged:(NSNotification *)note 
  
{ 
  
    Reachability *currentReach = [note  
  object]; 
  
    NSParameterAssert([currentReach isKindOfClass:[Reachability  
  class]]); 
  
    NetworkStatus status = [currentReach currentReachabilityStatus];  
  
 
  
     
  if (status == NotReachable) 
  
   { 
  
       UIAlert *alert = [[UIAlertView alloc] initWithTitle:NSLocalizedString( 
  @" 
  AppName 
  ",nil) 
  
  message: NSLocalizedString ( 
  @" 
  NotReachable 
  ",nil); 
  
   
  delegate:nil cancelButtonTitle: 
  @" 
  YES 
  "  
  
  otherButtonTitles:nil]; 
  
 
  
   [alert show]; 
  
   [alert release]; 
  
    } 
  
} 
  
 
  
 
  
 
  // 
  程序启动器，启动网络监视 
  
- ( 
  void)applicationDidFinishLaunching:(UIApplication *)application 
  
{ 
  
    
  // 
  ....

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

 

二、其他常用的类。

 1.NSURL

 2.NSURLRequest

 3.NSMutableURLRequest 是NSURLRequest的子类，可以设置一些请求参数

 4.NSURLResponse 

 5.NSError