android - 如何使用广播接收器更新 UI？

Question

我需要使用广播接收器更新 UI。我编写了这段代码，但在调试时没有看到 UI 的任何更新。

[BroadcastReceiver(Enabled = true)]
[IntentFilter(new[] { Android.Content.Intent.ActionTimeTick })]
private class broadcastReceiver : BroadcastReceiver
{
    private _MyActivityact;
    public void broadCastReceiver(_MyActivity act)
    {
        this.act = act;
    }

    public override void OnReceive(Context context, Intent intent)
    {
        _MyActivity.RunOnUiThread(() => {
                     updateUI(intent);   
        });                     
    }

    private void updateUI(Intent intent)
    {
        float mstartx = _MyActivity.getmStartX();
        TextView startx = _MyActivity.FindViewById<TextView>(Resource.Id.startx);
        startx.SetText(Convert.ToChar(mstartx));                 
    }
}

Answer 1

问题是您无法订阅ActionTimeTick你的方式。来自文档:

Broadcast Action: The current time has changed. Sent every minute. You cannot receive this through components declared in manifests, only by explicitly registering for it with Context.registerReceiver().

在 Xamarin 中，IntentFilter monodroid.exe 在生成 AndroidManifest.xml 文件中的 intent-filter 元素时使用该属性，因此该属性将不起作用。

您需要做的是删除 IntentFilter 属性并在您的 MainActivity 中以编程方式注册接收器(例如)。

protected override void OnResume()
{
    base.OnResume();
    RegisterReceiver(yourReceiver, new IntentFilter(Intent. ActionTimeTick));
}

protected override void OnPause()
{
    base.OnPause();
    UnregisterReceiver(yourReceiver);
}