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爲什麼視圖控制器不符合UIPickerViewDataSource？不符合協議「UIPickerViewDataSource」
我已經檢查了我能做的所有事情，從網上進行調試。
我已經鍵入了協議（Swift 3.1）的所有必要功能，但徒勞無功。
這裏是我的代碼：
class SelectClassViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
let grades = ["7", "8", "9", "10", "11", "12"]
var selectCurrentGrade : String? = nil
@IBOutlet weak var Grade: UIPickerView!
@IBAction func Next(_ sender: Any) {
if selectCurrentGrade != nil {
performSegue(withIdentifier: "GradeToClass", sender: self)
}
}
@IBAction func Back(_ sender: Any) {
performSegue(withIdentifier: "GradeToMain", sender: self)
}
override func viewDidLoad() {
super.viewDidLoad()
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return grades[row]
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return grades.count
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
selectCurrentGrade = grades[row]
}
}
}