網絡狀態檢測Reachability

#import "Reachability.h"

@interface JRViewController ()<UIActionSheetDelegate>
@property(nonatomic,strong)  Reachability * reach;
@end
@implementation JRViewController

(void)viewDidLoad {
  [super viewDidLoad];

//監聽Reachability.h————————————————————————————————————————————————————————————————

//
[self monitorNetState:nil];

// 開啟通知監控，實時等待
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(monitorNetState:) name:kReachabilityChangedNotification object:nil];//object是指監聽誰發出的通知，在這里可以寫self.reach,也可以寫nil
[self.reach startNotifier];//一定要寫開始監控


}
//**
//reachability監聽————————————————————————————————————————————————————————————————

(void) monitorNetState:(NSNotification *)noti
{
  NSLog(@"%@", noti);
  if(self.reach==nil)//
  {
  self.reach=[Reachability reachabilityForInternetConnection];//不是單例



    //他還有兩個子類

//        ReachableViaWiFi;
//        ReachableViaWWAN;

}

if(self.reach.currentReachabilityStatus!=NotReachable)
{

    if (self.reach.currentReachabilityStatus==ReachableViaWiFi)
    {
        NSLog(@"wifi");
    }
    else
    {
        NSLog(@"3g/2g");
    }
}
else
{
    NSLog(@"沒有網");
}

}
//移除監聽
-(void)dealloc{
    //reachability需要自己停止
    [self.reach stopNotifier];

[[NSNotificationCenter defaultCenter] removeObserver:self];

}
@end </pre>