UIPickerView depending on first component - ios

Question

So I have a UIPickerView with two components. The first one called "Cupboards", the second "Drawer". They have a one to many relationships in CoreData Cupboards <-->> Drawer. I would like that if I select a Cupboard, only the matching Drawers get displayed. I'm not sure how to get that working with the relationship.
That's what I have for showing the Cupboard:
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 2
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if(component==0){
return cupboards.count
}
xxxx
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
if(component==0){
return cupboards[row].name
}
xxxx
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if(component==0){
}
}
Thank you in advance
Update:
Got it like that now, but I get no results.
var cupboardDrawers = [Drawer]()
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if(component==0){
let request: NSFetchRequest<Drawer> = Drawer.fetchRequest()
request.predicate = NSPredicate(format: "cupboard == %#", cupboards[row].name!)
do{
let result = try mgdContext.fetch(request)
cupboardDrawers = result
addEatDataPicker.reloadAllComponents()
}catch{
print(error.localizedDescription)
}
}
}

Answer 1

You need to create and update a cupboardDrawers array with the fetching results:
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 2
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if(component==0){
return cupboards.count
} else {
return cupboardDrawers.count
}
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
if(component==0){
return cupboards[row].name
} else {
return cupboardDrawers[row].yourProperty
}
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if(component==0){
// you can add this part to a separate function and call it here
cupboardDrawers = []
let request = NSFetchRequest<Drawer>(entityName:”Drawer”)
request.predicate = YourPredicate with cupboards[row].name
do {
let items = context.fetch(request)
guard items.count > 0 else {
print(“no items found”)
return
}
cupboardDrawers = items
//reload your picker
} catch {
print(error)
}
}
}