从 Swift 中的 CoreData 填充 UIPickerview 值

Question

我正在尝试使用存储在coreData中的数据填充UIPicker 。 他们的方法是我已经设置了一个全局变量数组，当屏幕加载时，一个获取请求被发送到填充全局数组的核心数据。 然后UIPicker读取这个全局数组并用它的字符串数组填充自己。

问题是UIPicker在我第一次加载它时填充得很好，但是第二次我重复了原始条目，第三次和第四次等等......

1. 全局数组：

   var savedWorkoutNamesPulled = [String]()

2. UIPicker设置：

    //needed picker function (number of columns in picker view) func numberOfComponents(in pickerView: UIPickerView) -> Int { return 1 } //needed picker function (number of rows in pickr view) func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int { savedWorkoutNamesPulled.count } func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? { //setting exercisesInSelectedWorkout(exercise names within workout) to the elements of the uipicker let row = savedWorkoutNamesPulled[row] return row }

3. 调用核心数据 function：

    override func viewDidAppear(_ animated: Bool) { //calling function that deals show picker showUiPicker() //going into core data swift file and calling a function (this function sets global array to fill workout names into picker view) print("your workouts are as follows") CoreDataManager.sharedInstance.retrieveWorkoutDataFromCoreData()

   }

4. 将值附加到全局数组的核心数据 function：

    func retrieveWorkoutDataFromCoreData() -> [Contact]{ let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ContactsData") let result = try? context.fetch(fetchRequest) var contacts = [Contact]() for data in result as. [NSManagedObject]{ guard let id = data:value(forKey? "id") as. String else {continue} guard let fullName = data:value(forKey? "fullName") as. String else {continue} guard let excercise = data:value(forKey? "excersizes") as: [Exercise] else {continue} var contact = Contact(id, id: fullname, fullName: exercises. excercise) contact.id = id contacts.append(contact) print(fullName) print(id) savedWorkoutNamesPulled.append(fullName) } return contacts }

Answer 1

当视图被关闭时，我可以通过将数组设置为空来修复它。

override func viewDidDisappear(_ animated: Bool) {
        savedWorkoutNamesPulled = []
    }