there are two error in your code above:
1.Xamarin.Forms.Forms.Context
could not get the correct context.
you could defined a static variable in MainActiviy like :
public static MainActivity Instance;
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
Instance = this;
LoadApplication(new App());
}
you also could use the Current Activity Plugin,you could refer to Current Activity
2.After Android6.0 you should requests the runtime permissions and the official doucument
here is a simple example:
[assembly: Xamarin.Forms.Dependency(typeof(PhoneCall_Droid))]
namespace App18.Droid
{
class PhoneCall_Droid: IPhoneCall
{
public void MakeQuickCall(string PhoneNumber)
{
try
{
if(ActivityCompat.CheckSelfPermission(MainActivity.Instance, Android.Manifest.Permission.CallPhone) != Android.Content.PM.Permission.Granted ){
ActivityCompat.RequestPermissions(MainActivity.Instance, new string[] {Android.Manifest.Permission.CallPhone }, 1);
return;
}
else
{
var uri = Android.Net.Uri.Parse(string.Format("tel:{0}", PhoneNumber));
var intent = new Intent(Intent.ActionCall, uri);
MainActivity.Instance.StartActivity(intent);
}
}
catch (Exception ex)
{
new AlertDialog.Builder(MainActivity.Instance).SetPositiveButton("OK", (sender, args) =>
{
//User pressed OK
})
.SetMessage(ex.ToString())
.SetTitle("Android Exception")
.Show();
}
}
}
}
and you also could to use the nugetpackage Plugin.Permissions to request runtime permissions(Permission.Location)
refer to Plugin.Permissions
finally you could call like
DependencyService.Get<IPhoneCall>().MakeQuickCall(phonenumber);