Has anyone tried reading and writing a file in a single app? If so, please share this woud be a huge help
Please make an attempt to figure it out yourself and then come back with specific questions.
ISTR they have - and posted about it here.
Have you tried a search … ?
Actually I need to store values for at least 6 hours before pushing them to the cloud. These values are from network of devices communicating over bluetooth. Can you suggest a better way to do this rather than storing to file and then reading it? It would a huge help.
PS The cloud also send some messages for the the devices and I need to store them too and then communicate it. If I could your ideas for this, it mean the world. Thanks 
Saving to file sounds like a reasonable approach.
If you know that you can retain power for 6 hours (or don’t mind losing the data in the event of a power failure), you could just keep the data in RAM.
Great. Thanks for all your help.