ASIHTTPRequet网络相关设置

取消网络请求：

-(void)dealloc
{

    [postData clearDelegatesAndCancel];
    postData = nil;
}

判断当前是否有网络
/***
 * 此函数用来判断是否网络连接服务器正常
 * 需要导入Reachability类
 */
- (BOOL)isExistenceNetwork
{
    BOOL isExistenceNetwork;
    Reachability *reachability = [Reachability reachabilityWithHostName:@"www.apple.com"];  // 测试服务器状态
    
    switch([reachability currentReachabilityStatus]) {
        case NotReachable:
            isExistenceNetwork = FALSE;
            break;
        case ReachableViaWWAN:
            isExistenceNetwork = TRUE;
            break;
        case ReachableViaWiFi:
            isExistenceNetwork = TRUE;
            break;
    }
    return  isExistenceNetwork;
}