You can add formulas to a view to build advanced filters.
The formula must return YES (Boolean value) if the condition is satisfied, otherwise NO (Boolean value).
Filter by the current day
In the following example we'll add a formula to filter the documents that match the current day only.
Open a collection and tap on the button → Select New view.
Tap on the button to add a new condition.
Tap on the Date field.
In the condition, tap on the operator → Select Formula.
In the condition, tap on Any.
Tap on the button in the formula editor.
Tap on the Date in unit function. This function checks that a date is included in a specified range.
Tap on the button in the formula.
Tap on the Date field.
Formula is completed, tap on the Save button. Tip: you can also filter by month or year just by changing the second parameter of the function.
Tap on Save this view to save the view.