【代码笔记】判断有无网络

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

#import "RootViewController.h"

//加入头文件
#import "Reachability.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.

if ([self isConnectionAvailable]) {

UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"提醒" message:@"网络已连接，请您一会儿重新发送" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil];
[alert show];

};
}
#pragma -mark -functions
//判断网络是否连接。
-(BOOL) isConnectionAvailable{

BOOL isExistenceNetwork = YES;
Reachability *reach = [Reachability reachabilityWithHostName:@"www.apple.com"];
switch ([reach currentReachabilityStatus]) {
case NotReachable:
isExistenceNetwork = NO;
//NSLog(@"notReachable");
break;
case ReachableViaWiFi:
isExistenceNetwork = YES;
//NSLog(@"WIFI");
break;
case ReachableViaWWAN:
isExistenceNetwork = YES;
//NSLog(@"3G");
break;
}
if (!isExistenceNetwork) {

UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"提醒" message:@"网络未连接，请您一会儿重新发送" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil];
[alert show];
}
return isExistenceNetwork;
}