W. *_*ook 4 uipickerview ios swift
我有一个视图，其中包含三个选择器视图。两个选择器视图具有相同的数据，一个包含数字 1 到 100 的数组。第三个选择器视图包含一个包含模型铁路轨道制造商列表的数组。我使用我在本网站上找到的方法标记了选择器视图，但是当我运行该应用程序时，所有三个选择器视图的数据都为 1 到 100。我还从所有选择器视图控制拖动到视图顶部的黄色圆圈，然后单击dataSource和delegate。如何在一个视图中使用具有不同数据源的多个选择器视图？另外，为了使代码运行，我不得不从所有@IBOutlet 中删除弱与选择器视图相关的声明。这是一件坏事吗？我对代码比较陌生。谢谢。
import UIKit
class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {
//MARK: Properties
@IBOutlet var layoutLengthPickerView: UIPickerView!
@IBOutlet var layoutWidthPickerView: UIPickerView!
@IBOutlet var trackPickerView: UIPickerView!
override func viewDidLoad() {
super.viewDidLoad()
layoutLengthPickerView = UIPickerView()
layoutWidthPickerView = UIPickerView()
trackPickerView = UIPickerView()
layoutLengthPickerView.tag = 0
layoutWidthPickerView.tag = 1
trackPickerView.tag = 2
}
let numbers = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "100"]
let manufacturers = ["Atlas True Track", "Atlas Code 100", "Atlas Code 83", "Bachmann Nickel Silver", "Bachmann Steel Alloy", "Kato", "Life-Like Trains Code 100", "LIfe-Like Trains Power-Loc", "Peco Code 100", "Peco Code 83", "Peco Code 75", "Shinohara Code 100", "Shinohara Code 70", "Walthers"]
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
if pickerView.tag == 0 {
return numbers[row]
} else if pickerView.tag == 1 {
return numbers[row]
} else if pickerView.tag == 2 {
return manufacturers[row]
}
return ""
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if pickerView.tag == 0 {
return numbers.count
} else if pickerView.tag == 1 {
return numbers.count
} else if pickerView.tag == 2 {
return manufacturers.count
}
return 1
}
}
当处理具有委托和数据源的多个控件时，您应该考虑通过为多个选择器的委托创建单独的对象来避免视图控制器膨胀（即，本着单一职责原则的精神）。这使此逻辑脱离了视图控制器本身，并避免了尝试为多个选择器提供毛发-或语句的单一麻烦UIPickerViewDataSource和UIPickerViewDelegate方法。ifelseswitch
例如，这里是具有网点两个采摘视图控制器，而不是拖累的代码视图控制器来管理dataSource，并delegate为这些拾贝，你可以有单独的对象针对每个挑选，所有的视图控制器所要做的就是说哪个委托对象将处理哪个选择器：
class ViewController: UIViewController {
@IBOutlet weak var namePicker: UIPickerView!
@IBOutlet weak var numberPicker: UIPickerView!
let namePickerDelegate = NamePickerDelegate()
let numberPickerDelegate = NumberPickerDelegate()
override func viewDidLoad() {
super.viewDidLoad()
namePicker.delegate = namePickerDelegate
namePicker.dataSource = namePickerDelegate
numberPicker.delegate = numberPickerDelegate
numberPicker.dataSource = numberPickerDelegate
}
@IBAction func didTapButton(_ sender: Any) {
let nameValue = namePicker.selectedRow(inComponent: 0)
let numberValue = numberPicker.selectedRow(inComponent: 0)
print("\(nameValue); \(numberValue)")
}
}
唯一的技巧是确保保持对这些委托对象的强引用，如上所示，因为选择器本身只有对其委托的弱引用，这是最佳实践。
选择器委托方法的实现更加清晰：
class NamePickerDelegate: NSObject, UIPickerViewDataSource, UIPickerViewDelegate {
let names = ["Mo", "Larry", "Curley"]
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return names.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return names[row]
}
}
class NumberPickerDelegate: NSObject, UIPickerViewDataSource, UIPickerViewDelegate {
let numbers: [String] = {
let formatter = NumberFormatter()
formatter.numberStyle = .spellOut
return (0 ..< 100).compactMap { formatter.string(for: $0) } // use `flatMap` in Xcode versions prior to 9.3
}()
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return numbers.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return numbers[row]
}
}
现在，这显然仍然是一个简化的示例，但美妙之处在于，随着代码变得越来越复杂，细节被封装在单独的对象中，而不是将所有代码都放在一个视图控制器中。
如果需要，您可以让视图控制器向委托/数据源对象提供字符串列表。事实上，这简化了它，因为您只需要一个选择器委托的类，并且您只需为每个选择器实例化一个不同的类：
class ViewController: UIViewController {
let names = ["Mo", "Larry", "Curley"]
let numbers: [String] = {
let formatter = NumberFormatter()
formatter.numberStyle = .spellOut
return (0 ..< 100).compactMap { formatter.string(for: $0) } // use `flatMap` in Xcode versions prior to 9.3
}()
@IBOutlet weak var numberPickerOne: UIPickerView!
@IBOutlet weak var numberPickerTwo: UIPickerView!
@IBOutlet weak var namePicker: UIPickerView!
lazy var numberPickerOneDelegate: PickerDelegate = PickerDelegate(strings: self.numbers)
lazy var numberPickerTwoDelegate: PickerDelegate = PickerDelegate(strings: self.numbers)
lazy var namePickerDelegate:PickerDelegate = PickerDelegate(strings: self.names)
override func viewDidLoad() {
super.viewDidLoad()
numberPickerOne.delegate = numberPickerOneDelegate
numberPickerOne.dataSource = numberPickerOneDelegate
numberPickerTwo.delegate = numberPickerTwoDelegate
numberPickerTwo.dataSource = numberPickerTwoDelegate
namePicker.delegate = namePickerDelegate
namePicker.dataSource = namePickerDelegate
}
}
class PickerDelegate: NSObject, UIPickerViewDataSource, UIPickerViewDelegate {
let strings: [String]
init(strings: [String]) {
self.strings = strings
super.init()
}
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return strings.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return strings[row]
}
}
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