百度地图 气泡在地图初始化的时候就出现
一定要在添加过BMKPointAnnotation后再设置selectAnnotation 为YES 否则没反应不显示
self.annotation=[[BMKPointAnnotation alloc]init];
self.annotation.coordinate = CLLocationCoordinate2DMake(latitude, longitude);
self.annotation.title = model.estate_name;
self.annotation.subtitle = @"";
[_mapView addAnnotation:self.annotation];
[self.mapView selectAnnotation:self.annotation animated:YES];
