Mobile App integration and Validation

The project is about revising an android apps so that it can connected to the API's properly (knows when to hit the API) while also using redux to give smooth access to user (only use API's when new data needs to be updated) 1 We have build a mobile app that have problem in integrating with the API. Problem exists : A. To have a validation in each screen of user input. So that user will input only what is required by the API. Validation is resulting pop ups notifying user and also returning user to the exact place where user need to revise B. Currently user can only know the problem at the end of the stage. What we need is the user to know at each stage if their input is right or their input is wrong 2 To have a redux / session system enabled so that FE is not always use the API to return datas to user 3 When redux is applied. the redux is also needs to know if the session needs to be refreshed. i.e when user change the quantity of the stocks available. The redux knows that it needs to update the data. So that redux is not applied and FE gets the data via API to update the stocks available 4 When user is entering one of features, if something goes wrong, the apps needs to check first whether the users connection (internet) is available or not. If not, then return info about the connection. If yes, then check error