iOS & Android mobile app for an association

I'm running a software company and because of I have no time for a new project, I need another team/developer to accomplish a project for me. Our customer (a local association) want a mobile application to keep continuous connection with his clients/fans. The main purpose is that the organization will send publish events, blog news and images on the application and the users will follow it using the application on their device (iOS & Android) Main expectations of the application: - a home page / dashboard (with a menu) - a gallery (with albums) - news/blog - contact page + location - events page The application must be developed for iOS and Android. Cross-platform HTML development is preferred but we are open for suggestions. A PHP web application should also be created where the administrator(s) will be able to update data (such as blog, events, gallery, ..). The data will be stored in an external database (on the web). The web application can have a basic design but the for the mobile app I want a user-friendly and a pretty nice layout. No login is needed for the mobile application. Everyone will be able to download it from the appropriate market. Only the web application will use authorization to grant the admin access. When the application is opened and there is internet connection, it will update data from the internet/database (except the gallery). So it can also work offline, when there is no internet connection. Only for the gallery is internet connection required, this for keeping the local storage on the device as small as possible. This will be the first stage of development of this application. In the future, many functions and modules will be added to the system to make it a global and ultimate application with great functions. The ones who have developed something similar and show it to me will prevail. Thank you all