title: how to fire timer when create the timer inside block function?
body: <pre><code>@interface Taxi_MainViewController : Taxi_BaseNavViewController
  {
    __block NSTimer *timer_;
  }
  
  
  
    [Taxi_do_order psg_place_orderWithMemberId:strMemberId_ orderStatus:K_orderStatus_open andCLLocationCoord:location.coordinate callback:^(NSInteger iOrderId){
          [Taxi_StatusView dismiss];
          if (iOrderId &gt;=0)
          {
              isOrderExist = YES;
              [weakSelf_ showWaittingDriverAcceptView];
              timer_ =   [NSTimer scheduledTimerWithTimeInterval:2.0
                                                                 target:weakSelf_
                                                               selector:@selector(actListen:)
                                                               userInfo:nil
                                                                repeats:YES];
          }else
              [weakSelf_ hideWaittingDriverAcceptView];
      }faile:^(){
          [Taxi_StatusView showLostNetWork];
      }];
  </code></pre>
  
  <p>when i call [timer_ invalidate],timer_ = nil; at other method, the timer function still call every 2 second. </p>