Hi @ihebc ,
Could you please share a bit more about your scenario?
Do you want to calculate the calculated field within your app when you change the Dates value?
If you want to calculate the calculated field within your app when you change the Dates value, I afraid that there is no way to achieve your needs in PowerApps.
Currently, the Calculated field in SP List would be rendered as Read-Only field in PowerApps app. We could not specify/assign any value for this Calculated field in PowerAps app. The Calculated field would be calculated by SP System after you add a new record or edit an existing record.
As an alternative solution, I think it is not necessary to add a Calculated field in your SP list to store the date value difference, instead, you could consider add a Number value within your SP List, then do the date value difference calculation (using DateDiff function) within your app, then save the result back to the Number field in your SP list.
On your side, please consider add a Number field, called "DateDifference". Then re-generate a new app based on your SP list. Within the Edit form, set the Default property of the Text Input box within the DateDifference data card to following:
DateDiff(DuDatePicker.SelectedDate, AuDatePicker.SelectedDate, Days) /* <-- I assume that the Du represents the Start date, Au represents the End date */
or
Value(DateDiff(DuDatePicker.SelectedDate, AuDatePicker.SelectedDate, Days))
Please consider take a try with above alternative solution, then check if the issue is solved.
Best regards,
