Xcode Swift 3 Picker：将数据源放入 ViewDidLoad

Question

我正在尝试设置一个根据特定条件显示不同结果的选择器。唯一的问题是我需要将 dataSource（将显示的选择器数据）放在 viewDidLoad 之外。如果满足条件，我需要 viewDidLoad 加载适当的数据。但是，对于我所见过的处理选择器的代码，dataSource 数组似乎位于 viewDidLoad 之外（我想委托方法可以使用该值）。我只是想知道我是否可以将这个 dataSource 放入 viewDidLoad 以便它能够识别它，或者是否有办法运行在 [=14= 之外的 Switch 或 If 语句] 和 class.

import UIKit
import Parse

class VC: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    var pickerData = [String]()

    @IBOutlet weak var namePicker: UIPickerView!

    override func viewDidLoad() {
        super.viewDidLoad()

        namePicker.dataSource = self
        namePicker.delegate = self


        //here I want the picker to show something different depending on the value of nameOfPerson. I changed the order of the array because the picker selects the first name of the array as the default. 
        switch nameOfPerson
        {
        case "Carly": 
            let pickerData = ["Carly","Jeff","Bob","Anita"]
        case "Jeff": 
            let pickerData = ["Jeff","Carly","Bob","Anita"]
        case "Bob": 
            let pickerData = ["Bob","Carly","Jeff","Anita"]
        case "Anita": 
            let pickerData = ["Anita","Carly","Jeff","Bob"]
        }
    }
   func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
    }
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return pickerData.count
    }
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return pickerData[row]
    }
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
    {

    }
}

Answer 1

需要在加载视图时设置数据源，但您可以在任何需要的地方加载它。

里面viewDidLoad

picker.datasource = self

任何地方都可以设置实际数据；

picker.dataArray = "example, anything"

我不确定我是否完全理解您的意思。如果您不需要这个，请告诉我。

Answer 2

I am just wondering if I can place this dataSource into viewDidLoad so that it would recognize it, or if there was a way to run a Switch or If statement outside the viewDidLoad and in the class

没有。数据源方法必须是 methods，即 class 顶层的函数，以便 Objective-C 可以看到它们。因此，数据本身必须对数据源方法可见，并且在 viewDidLoad 和数据源方法之间共享数据的唯一连贯方式是属性，就像您的 var pickerData。

你的代码有什么问题是 let:

    case "Carly": 
        let pickerData = ["Carly","Jeff","Bob","Anita"]
    case "Jeff": 
        let pickerData = ["Jeff","Carly","Bob","Anita"]
    case "Bob": 
        let pickerData = ["Bob","Carly","Jeff","Anita"]
    case "Anita": 
        let pickerData = ["Anita","Carly","Jeff","Bob"]
    }

从每个案例中删除术语 let！否则你只是在设置一个临时局部变量 pickerData，这不是你想要做的。您想要设置您声明的属性：

var pickerData = [String]()

...而您的代码没有这样做！你要的是这个：

case "Carly": 
    self.pickerData = ["Carly","Jeff","Bob","Anita"]
case "Jeff": 
    self.pickerData = ["Jeff","Carly","Bob","Anita"]
case "Bob": 
    self.pickerData = ["Bob","Carly","Jeff","Anita"]
case "Anita": 
    self.pickerData = ["Anita","Carly","Jeff","Bob"]
}

（当然，你还需要 default 箱子。）

然后，最后为了保险起见，重新加载数据：

self.namePicker.reloadAllComponents()

Xcode Swift 3 Picker：将数据源放入 ViewDidLoad

Xcode Swift 3 Picker: Putting the DataSource in ViewDidLoad

swift

delegates

iboutlet

viewdidload

picker