Swift - 返回存储在结构中的元素

Question

如何检索存储在结构体数组中的元素？我想在加载 View 时显示艾伯塔省行。

查看时将出现:

selectedProvince = client?.province 我从服务器/数据库获取 AB。我想在 pickerview 上显示艾伯塔省。目前显示的是AB。

点击文本字段时会显示选取器 View 。因此，AB 是该文本字段的值。

我使用选择器 View 来显示名称，选择后我将缩写存储在变量中。之后，数据被保存。

当我加载 View 时，我加载数据。省份的存储方式如 AB 所示。

struct Province {
    let name, abbrev : String
}



let provinces = [Province(name: "Alberta", abbrev: "AB"), Province(name: "British Columbia", abbrev: "BC"),
                 Province(name: "Manitoba", abbrev: "MB"), Province(name: "New Brunswick", abbrev: "NB"),
                 Province(name: "Newfoundland and Labrador", abbrev: "NL"), Province(name: "Northwest Territorie", abbrev: "NT"),
                 Province(name: "Nova Scotia", abbrev: "NS"), Province(name: "Nunavut", abbrev: "NU"),
                 Province(name: "Ontario", abbrev: "ON"), Province(name: "Prince Edward Island", abbrev: "PE"),
                 Province(name: "Quebec", abbrev: "QC"), Province(name: "Saskatchewan", abbrev: "SK"),
                 Province(name: "Yukon", abbrev: "YT")]


var client: Client?
var selectedProvince: String?

override func viewWillAppear(_ animated: Bool) {
    self.title = "New"
    if (client?.client_id) != nil {
        self.title = "Edit"
        nameTextField.text = client?.name
        provinceTextField.text = client?.province
        cityTextField.text = client?.city
        addressTextField.text = client?.address
        postalCodeTextField.text = client?.postal_code
        selectedProvince = client?.province            
    }
}



override func viewDidLoad() {
    super.viewDidLoad()
    tableView.sectionHeaderHeight = 50.0;

    navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Save", style: .plain, target: self, action: #selector(save))


    let thePicker = UIPickerView()
    provinceTextField.inputView = thePicker
    thePicker.delegate = self

    // ToolBar
    let toolBar = UIToolbar()
    toolBar.barStyle = .default
    toolBar.isTranslucent = true
    toolBar.tintColor = UIColor(red: 92/255, green: 216/255, blue: 255/255, alpha: 1)
    toolBar.sizeToFit()

    // Adding Button ToolBar
    let doneButton = UIBarButtonItem(title: "Done", style: .plain, target: self, action: #selector(ClientDetailViewController.doneClick))
    let spaceButton = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
    let cancelButton = UIBarButtonItem(title: "Cancel", style: .plain, target: self, action: #selector(ClientDetailViewController.cancelClick))
    toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)
    toolBar.isUserInteractionEnabled = true
    provinceTextField.inputAccessoryView = toolBar

}

@objc func doneClick() {
    provinceTextField.resignFirstResponder()
}
@objc func cancelClick() {
    provinceTextField.resignFirstResponder()
}

// MARK: - Picker view
func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

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

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

func pickerView( _ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    provinceTextField.text = provinces[row].name
    selectedProvince = provinces[row].abbrev
}

Answer 1

首先，您需要对选择器 View 的强引用，这是顶层的属性:

var thePicker = UIPickerView()

并在viewDidLoad中设置参数

provinceTextField.inputView = thePicker
thePicker.delegate = self

在 viewWillAppear 中检查 selectedProvince 是否不 nil 并(安全地)获取 Province 实例的索引。然后设置对应的行

selectedProvince = client?.province
if let province = selectedProvince, 
   let index = provinces.index(where: { $0.abbrev == province }) {
      thePicker.selectRow(index, inComponent: 0, animated: false)
}