Delegate Methods in Swift for UIPickerView

Question

Just getting started in Swift and having trouble calling the delegate methods for a UIPickerView

So far I have added the UIPickerViewDelegate to my class like so:

class ExampleClass: UIViewController, UIPickerViewDelegate

I have also created my UIPickerView and set the delegate for it:

@IBOutlet var year: UIPickerView
year.delegate = self

Now I am just having trouble turning the following into Swift code:

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView

Any help would be appreciated

Answer 1

That's actually a method in the UIPickerViewDataSource protocol, so you'll want to make sure you set your picker view's dataSource property as well: year.dataSource = self. The Swift-native way seems to be to implement protocols in class extensions, like this:

class ExampleClass: UIViewController {
    // properties and methods, etc.
}

extension ExampleClass: UIPickerViewDataSource {
    // two required methods

    func numberOfComponentsInPickerView(pickerView: UIPickerView!) -> Int {
        return 1
    }

    func pickerView(pickerView: UIPickerView!, numberOfRowsInComponent component: Int) -> Int {
        return 5
    }
}

extension ExampleClass: UIPickerViewDelegate {
    // several optional methods:

    // func pickerView(pickerView: UIPickerView!, widthForComponent component: Int) -> CGFloat

    // func pickerView(pickerView: UIPickerView!, rowHeightForComponent component: Int) -> CGFloat

    // func pickerView(pickerView: UIPickerView!, titleForRow row: Int, forComponent component: Int) -> String!

    // func pickerView(pickerView: UIPickerView!, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString!

    // func pickerView(pickerView: UIPickerView!, viewForRow row: Int, forComponent component: Int, reusingView view: UIView!) -> UIView!

    // func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int)
}