Uipickerviewdelegate Xcode 8 Swift 3

Xcode 8 / Swift 3 : Simple UIPicker code not working

UIPickerViewDataSource method numberOfComponentsInPickerView is changed in Swift 3 like this that is the reason you are getting this error.

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return muteForPickerData.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return muteForPickerData[row]
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

}

For more detail read Apple Documentation on UIPickerView.

Note: You need to also add _ as first parameter label same like other methods in your UIPickerViewDelegate method that is titleForRow and didSelectRow.

UIPickerView on Swift 3

Use this method, see the use of _ before pickerview. That is the only problem

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

    }

list of countries into uipickerview swift 3

You need to return array count in method numberOfRowsInComponent and in the titleForRow you need to return array object, show that it will show in picker.

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return countries.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return countries[row]
}

PickerView: Type 'ViewController' does not conform to protocol 'UIPickerViewDataSource'

The method signature for numberOfComponents(in:) changed from iOS 9.3 to iOS 10. Since you are targeting a legacy version of Swift, replace your current implementation of numberOfComponents(in:) with the appropriate version below.

Swift 2.3

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

Swift 3

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

---

The API changes can be seen here: https://developer.apple.com/library/content/releasenotes/General/iOS10APIDiffs/Swift/UIKit.html

Modified UIPickerViewDataSource

Declaration

From

protocol UIPickerViewDataSource : NSObjectProtocol {
    func numberOfComponentsInPickerView(_ pickerView: UIPickerView) -> Int
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
}

To

protocol UIPickerViewDataSource : NSObjectProtocol {
    func numberOfComponents(in pickerView: UIPickerView) -> Int
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
}

How conform to UIPickerViewDelegate and UIPickerViewDataSource outside of a ViewController?

When I attempt to define a separate class called 'PickerDelegate' that conforms to UIPickerViewDelegate & UIPickerViewDataSource, I get this error in Xcode:

Simply make your PickerDelegate a subclass of NSObject.

class PickerDelegate : NSObject, UIPickerViewDelegate, UIPickerViewDataSource {

This is no imposition, and is necessary, because Cocoa is Objective-C and won't even be able to see your delegate and data source methods otherwise.

swift picker view with numbers displaying question marks

Your problem is with the following:

private func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> Int? {
    return numbers[row]
}

This method should not be private and it should have the proper signature. This delegate method needs to return an optional String, not an optional Int.

private func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return String(numbers[row])
}

How to use two UIPickerViews in one view controller?

Based on the information I have in the question, I'd say that you need to set up the data source & delegate methods to handle the ability to distinguish between which picker instance is calling them.

Using the tag property on the picker view is one strategy.

There should be some if/else or switch statements in the methods that have varying logic depending on whether it's the location or the position picker that's being referenced.

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