UIPickerView not displaying data even after requery - ios

Question

Let's say I have a stream of dogs private var dogs: Observable<[Dogs]>. Every time a new value is produced my block is called where I create a new dataSource and delegate for my UIPickerView and then within the block I call pickerView.reloadAllComponents() but my view appears with an empty pickerView, even though the dataSource and delegate are queried.
Example code:
self.dataStream
.subscribeNext {
self.dataSource = PickerViewDataSource(data: $0)
self.pickerView.dataSource = self.dataSource
self.delegate = PickerViewDelegate(data: $0, selectedRow: self._selectedRowStream)
self.pickerView.delegate = self.delegate
self.pickerView.reloadAllComponents()
}.addDisposableTo(self.disposeBag)
Debugging the dataSource and delegate I know these are queried and the reason I am keep dataSource and delegate reference in the UIViewController is due to the fact that the UIPickerView holds a weak reference for these.
This one of the last strategies I have tried and still get the same result. Any help would be appreciated. Thanks.
Update:
DogPickerViewDataSource:
class DogPickerViewDataSource: NSObject, UIPickerViewDataSource {
private var dogs: [Dog]
init(
dogs: [Dog]
) {
self.dogs = dogs
}
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return dogs.count
}
}
DogPickerViewDelegate:
class DogPickerViewDelegate: NSObject, UIPickerViewDelegate {
private var selectedRow: BehaviorSubject<Int>
private var dogs: [Dog]
init(
dogs: [Dog],
selectedRow: BehaviorSubject<Int>
) {
self.dogs = dogs
self.selectedRow = selectedRow
}
func pickerView(pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
let dogName = (self.dogs[row].name)!
return NSAttributedString(string: dogName)
}
func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
self.selectedRow.onNext(row)
}
}

Answer 1

If I understand you correctly, on viewDidLoad you're initialising your pickerView with new delegate and data source, calling reloadAllComponents and expecting that everything should be displayed properly. But you're still displaying pickerView from previous view controller. You should try to hide picker view on previous view controller's viewWillDisappear method and display new one in viewDidAppear method of new view controller.