xamarin.forms - 我想在 iOS 的 Xamarim 表单中接收物理键盘按键

Question

我想在 iOS 的 Xamarim 表单中接收物理键盘按键。以下代码从这个链接很好地工作：

是否可以在应用程序级别挂钩硬件键盘事件？

但它仅适用于数字键。它不适用于像“A”这样的字母。添加如下图。

UIKeyCommand 加速器A = UIKeyCommand.Create((NSString)"A", 0, 选择器); AddKeyCommand（加速器A）；

任何不适合字母表的原因。我是否必须设置键盘类型。如果是怎么办？

代码从这里开始：

using Foundation;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(MobileProject.MainPage), typeof (com.YourCompany.iOS.KeyboardHookRenderer))]
namespace com.YourCompany.iOS
{
public class KeyboardHookRenderer : PageRenderer
{
    private string _RecvValue = string.Empty;

    public override bool CanBecomeFirstResponder
    {
        get { return true; }
    }

    protected override void OnElementChanged(VisualElementChangedEventArgs e)
    {
        base.OnElementChanged(e);
        string key = string.Empty;
        var selector = new ObjCRuntime.Selector("KeyRecv:");
        UIKeyCommand accelerator1 = UIKeyCommand.Create((NSString)"1", 0, selector);
        AddKeyCommand(accelerator1);
        UIKeyCommand accelerator2 = UIKeyCommand.Create((NSString)"2", 0, selector);
        AddKeyCommand(accelerator2);
        UIKeyCommand accelerator3 = UIKeyCommand.Create((NSString)"3", 0, selector);
        AddKeyCommand(accelerator3);

        ... etc as many as you need or use a loop based on key id...
    }

    [Export("KeyRecv:")]
    public void KeyRecv(UIKeyCommand cmd)
    {
        if (cmd == null)
            return;
        var inputValue = cmd.Input;
        if (inputValue == "\n" || inputValue == "\r")
        {
            ((MobileProject.MainPage) Element)?.HandleHardwareKeyboard(_RecvValue);
            _RecvValue = string.Empty;
        }
        else
        {
            _RecvValue += inputValue;
        }
    }
}
}

/// <summary>
/// Handle hardware keys (from KeyboardHookRender.cs in iOS project)
/// </summary>
/// <param name="keys">Keys sent, including trailing Cr or Lf</param>
public void HandleHardwareKeyboard(string keys)
{
    SomeTextbox.Text = keys;
    // Whatever else you need to do to handle it
}

标签： xamarin.formsxamarin.ios