ViewController的单触式UIPickerView ValueChange事件

本文关键字：ValueChange 事件 UIPickerView 单触式 ViewController | 更新日期: 2023-09-27 17:58:34

我想在UIPickerView更改其任何组件中的值时获取事件，以便我的UIViewController可以更改Labels。我只遇到了PickerView模型提供的一种有用的方法：

public override void Selected(UIPickerView pickerView, nint row, nint component)

当任何东西发生变化时，都会有相应的变化反映在模型中。但是，如果我想将这些更改反映回ViewController，我该怎么办？我想像iOS中的Delegates那样做这项工作。我对c#不太熟悉。感谢您的帮助。谢谢

public partial class ViewController : UIViewController  
{
    public override void ViewDidLoad()
        {
            base.ViewDidLoad();
            // Perform any additional setup after loading the view, typically from a nib.
            setupHandlers();
        }
   void setupHandlers()
        {
            pickerModel = new UnitPickerViewModel();
            pickerModel.Items = lengthArray;
            pickerModel.setDataForSecondComponent(lengthArray2);
            pickerView = new UIPickerView();
            pickerView.BackgroundColor = UIColor.LightGray;
            pickerView.DataSource = pickerModel;
        }
}

ViewController的单触式UIPickerView ValueChange事件

您可以创建弱和强Obj-C风格的委托：

强有力的代表：

在您的UIViewController类中创建嵌套的UIPickerViewDelegate类：

    class PickerDelegate : UIPickerViewDelegate
    {
        public override void Selected(UIPickerView pickerView, nint row, nint component)
        {
            base.Selected(pickerView, row, component);
            Console.WriteLine(row.ToString());
        }
    }

创建代表并将其分配给您的UIPickerView:

var picker = new UIPickerView(UIScreen.MainScreen.Bounds);
picker.DataSource = this;
picker.Delegate = new PickerDelegate();

弱势代表：

跳过嵌套类，将UIPicker选择的方法添加到UIViewController中，并用Foundation.Export:标记它

[Export("pickerView:didSelectRow:inComponent:")]
public void Selected(UIPickerView pickerView, nint row, nint component)
{
    Console.WriteLine(row.ToString());
}

将你的UIViewController指定为弱势代表：

var picker = new UIPickerView(UIScreen.MainScreen.Bounds);
picker.DataSource = this;
picker.WeakDelegate = this;
Add(picker);
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