我希望在一个场景中有多个UIPickerViews,而不使用委托函数使视图控制器膨胀。我在UIPickerViews上看到的所有教程都建议使用视图控制器本身作为UIPickerView
的委托。
如何将此委托代码移出ViewController
?
受this tutorial启发,这里有一个视图控制器,它将自己指定为UIPickerViews的委托。我对用于将行为映射到每个UIPickerView
的if/else逻辑持批评态度:
import UIKit
class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
@IBOutlet weak var pickerViewA: UIPickerView!
@IBOutlet weak var pickerViewB: UIPickerView!
let contentsA = ["1A", "2A", "3A"]
let contentsB = ["1B", "2B", "3B", "4B"]
override func viewDidLoad() {
super.viewDidLoad()
pickerViewA.delegate = self
pickerViewA.dataSource = self
pickerViewB.delegate = self
pickerViewB.dataSource = self
}
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1 //Applies to both pickerViewA & pickerViewB
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if pickerView == pickerViewA {
return contentsA.count
} else {
return contentsB.count
}
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
if pickerView == pickerViewA {
return contentsA[row]
} else {
return contentsB[row]
}
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if pickerView == pickerViewA {
// Do something A
} else {
// Do something B
}
}
}
理想情况下,我希望有一个符合这些协议的自定义类,然后为每个
UIPickerView
创建一个此类的新实例,以便它们具有唯一的委托和行为。当我试图定义一个名为“PickerDelegate”的独立类,它符合
UIPickerViewDelegate
&UIPickerViewDataSource
时,我在Xcode中得到这个错误:类型“PickerDelegate”不符合协议“NSObjectProtocol”
显然,从
UIPickerViewDelegate
继承。如果我添加协议存根(如Xcode所建议的那样),就会得到一长串我不喜欢实现的函数。在视图控制器之外,是否有更简单的方法来遵循这些协议?
最佳答案
当我试图定义一个名为“PickerDelegate”的独立类,该类符合UIPickerViewDelegate&UIPickerViewDataSource时,在Xcode中会出现此错误:
只需将PickerDelegate设为NSObject的子类。
class PickerDelegate : NSObject, UIPickerViewDelegate, UIPickerViewDataSource {
这不是强加的,而且是必要的,因为Cocoa是Objective-C,甚至不能看到委托和数据源方法。
关于ios - 如何在ViewController之外符合UIPickerViewDelegate和UIPickerViewDataSource?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/57138766/