I use the Xcode 8 and swift 2.3, but I met a problem the UIPickerView.dataSource = (self as! UIPickerViewDataSource) doesn't work when I try to use func of UIPicker, this is my code:
import UIKit
class ViewController: UIViewController {
let Num = ["1","2","3","4","5","6"]
@IBOutlet weak var UIPicker: UIPickerView!
override func viewDidLoad() {
super.viewDidLoad()
func numberOfRows(inComponent component: Int) -> Int {return 1}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {return Num.count}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {return Num[row]}
UIPicker.dataSource = (self as! UIPickerViewDataSource)
UIPicker.delegate = (self as! UIPickerViewDelegate)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
When I run my code, Xcode warning the code:
Could not cast value of type 'test.ViewController' (0x1000bd8c0) to
'UIPickerViewDataSource' (0x1ab289738). 2016-06-29 15:33:35.079300
test[474:98176] Could not cast value of type 'test.ViewController'
(0x1000bd8c0) to 'UIPickerViewDataSource' (0x1ab289738).
Yury :
Add UIPickerViewDataSource and UIPickerViewDelegate to the class declaration:\n\nclass ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate\n\n\nand don't use type casting using self:\n\noverride func viewDidLoad() {\n super.viewDidLoad()\n\n UIPicker.dataSource = self\n UIPicker.delegate = self\n}\n\n\nAlso you must move your methods out of viewDidLoad function, and correct them a bit:\n\nfunc numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {return 1}\n\nfunc pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {return Num.count}\n\nfunc pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {return Num[row]}\n\n\nNote that I highly recommend you to rename your Num and UIPicker properties to num and picker, so you will not mix them with class names\n\nUpd: full ViewController code:\n\nclass ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {\n\n let Num = [\"1\",\"2\",\"3\",\"4\",\"5\",\"6\"]\n\n @IBOutlet weak var UIPicker: UIPickerView!\n override func viewDidLoad() {\n super.viewDidLoad()\n\n UIPicker.dataSource = self\n UIPicker.delegate = self\n }\n\n func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {return 1}\n func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {return Num.count}\n func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {return Num[row]}\n}\n",
2016-06-29T07:44:50