在地图上默认显示注解，不用点击大头针就出来

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self addRestaurantAnnotation];
}

 //下面一句话使得注解初始在上面显示。
    [self.gooleMapView selectAnnotation:annotation animated:YES];
    [annotationArray addObject:annotation];
    [annotation release];
   
    [_gooleMapView addAnnotations:annotationArray];