I have this UITableView with custom cells that can get only predefined values, therefore I use a UIPickerView as their inputView. All is jolly good until I edit a field and
This reads like expected behavior - the picker belongs to a particular cell, that cell gets reloaded and is not the first responder any more. I guess one had to select a specific element anyway for the picker to appear, i.e. to make it first responder.
So you either need to make it become first responder again after reloading, or update the specific cell directly.