From my reading of the Esri web pages the Collector for ArcGIS is tightly tied to that platform. I would be delighted to learn that I am wrong about this.
I have a strong interest in generic mobile data collection apps for iOS and Android devices with GPSs. Particularly ones that can collect data while out of coverage, and then sync when they get back in to coverage. Ideally, they would also be able to cache portions of the data locally for use when off line.
What I envision is a web based application that allows one to specify your data layout, constraints, etc. and which will then generate the the backend database and allow access via a restful API.
What I need to do is enter data from a form on an mobile device, preferably both iOS and android, which will update tables in a backend database, potentially something with GIS extensions such as PostGIS. That would enable me to easily incorporate the data into QGIS. It must be able to work offline and many of the areas we work have not 3G coverage. Ideally you would be able to also cache selected data on the device for offline use. Map integrations is not important.
I have found some good cloud based solutions but I really want something where I have control of the back end data collection as some of the data is potentially sensitive. e.g. reporting sighting of rare reptiles which are a smuggling threat.
What alternatives are the for mobile apps to get data into QGIS.