Hello,
First of all, quite a interesting and unique project, thus, the reason why it got my intention and made me bid on it. I have a fair standard pickynes to choose unique and intresting, yet high quality projects, so that I remain motivated and excited to work on them, thus why I have quite a small number of projects in my profileI have done, yet if you check, all are 5 star rated and high quality unique projects.
I am also one of the very few "Preferred Freelancers" here in mobile phone (ios) category (despite always taking limited projects to work on).
I am a php, REST API and JSON webdev as well as a exclusive iOS-only mobile dev.
Now to answer your first question, I would never suggest anyone to ever get a app made anything but native unless its just a website or a static text content. There is no comparision of performance and flexibility a native app gives over some cross platform, web browser, html-jquery or non-native apps. Not to mention, its unprofessional.
I can create the app exactly as per the workflow you want except that I would like to suggest you maintaining your own image server and a API.
The api will be php based on REST standards and output in JSON.
The app will send the image to the API, it will host/save the image on the server, register a QR code to it (its url) and output the QR code back to the app. The app will then save the QR code in a local DB.
That QR code will be linked to the image hosted on your server.
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