我有一个Xamarin Forms项目,并实现了一个依赖服务来发送SMS,但是我不知道如何将与设备无关的回调转换为异步等待状态,以便可以将其返回。例如,在我的iOS实施中,我有类似以下内容:
[assembly: Xamarin.Forms.Dependency(typeof(MySms))]
namespace MyProject.iOS.DS
{
class MySms : IMySms
{
// ...
public void SendSms(string to = null, string message = null)
{
if (MFMessageComposeViewController.CanSendText)
{
MFMessageComposeViewController smsController= new MFMessageComposeViewController();
// ...
smsController.Finished += SmsController_Finished;
}
}
}
private void SmsController_Finished(object sender, MFMessageComposeResultEventArgs e)
{
// Convert e.Result into my smsResult enumeration type
}
}
我可以将public void SendSms
更改为public Task<SmsResult> SendSmsAsyc
,但是如何等待Finished回调并获取结果,以便我可以让SendSmsAsync
返回它?
答案 0 :(得分:1)
public interface IMySms
{
Task<bool> SendSms(string to = null, string message = null);
}
public Task<bool> SendSms(string to = null, string message = null)
{
//Create an instance of TaskCompletionSource, which returns the true/false
var tcs = new TaskCompletionSource<bool>();
if (MFMessageComposeViewController.CanSendText)
{
MFMessageComposeViewController smsController = new MFMessageComposeViewController();
// ...Your Code...
//This event will set the result = true if sms is Sent based on the value received into e.Result enumeration
smsController.Finished += (sender, e) =>
{
bool result = e.Result == MessageComposeResult.Sent;
//Set this result into the TaskCompletionSource (tcs) we created above
tcs.SetResult(result);
};
}
else
{
//Device does not support SMS sending so set result = false
tcs.SetResult(false);
}
return tcs.Task;
}
这样称呼:
bool smsResult = await DependencyService.Get<IMySms>().SendSms(to: toSmsNumber, message: smsMessage);