Museum Self-Guided Tour App Development

I am seeking a professional app developer who can create a self-guided tour app for my museum. The app should be compatible with both Android and iOS platforms. The freelancer must have a portfolio of similar apps, as this will significantly expedite the project. The app needs to support extensive video streaming, as well as offering audio guides and interactive images and text.

Key Features:
- QR Code Scanning: The app should utilize QR codes to provide additional content or information about specific exhibits.
- Offline Functionality: To accommodate visitors in areas with poor connectivity, the app should have an offline mode.
- Multi-Language Support: To cater to our diverse audience, the app must support multiple languages.

Navigation:
The app should feature map-based navigation, guiding users through the museum in an intuitive way.

Ideal Skills:
- Proficient in cross-platform app development (Android and iOS)
- Experience in creating apps with heavy video streaming content
- Understanding of implementing QR code functionalities
- Capable of integrating offline mode and multi-language support
- Knowledge of map-based navigation systems in apps
- Prior experience with similar self-guided tour apps is highly preferred.