Develop Reference

Android/Xamarin: How to launch dialog with broadcast receiver

I want my app to listen for intends broadcasted by the call application, and when a call intend is broadcasted for a specific number I want to launch a dialog. I read that "A broadcast receiver may not display dialogs, and it is strongly discouraged to start an activity from within a broadcast receiver" https://developer.xamarin.com/guides/android/application_fundamentals/broadcast-receivers/ so I am assuming I should instead make the broadcast receiver launch a service that then launches a dialog. Can anyone confirm this? Also any simplified examples would be highly appreciated
Thanks!

In the example below, the app uses a BroadcastReceiver to detect a phone call number and decide whether it should answer or not:
How to reject incoming call programatically in android?
So using a BroadcastReceiver for that isn't that bad.
If you just want to show information about the phone call, you can display an Notification, as suggested by Jon Douglas in the comments. Displaying Dialogs from BroadcastReceivers isn't allowed (also disencouraged).

Android: How to start activity when phone is sleeping, similar to Viber incomming call activity

I am developing an app and this app needs to give a clear indication to the user when some event happens.
Only thing I could do until now is giving a notification in the notification area. But, I need to give a more visible notification, similar to the behavior when phone is ringing in an incoming call.
As I can understand, the reason why android is only allowing apps to give a notification is to prevent apps from disturbing the user. But, this app I am developing plays a vital role in the job of the user, so I don't think it is inappropriate to give a such strong notification.
I know it should be doable since apps like Viber can start an activity similar to a incoming phone call, even when the device is sleeping.
Does anyone know how to get this done?

Register a broadcast receiver, and add a custom action to it say CustomAction.Instead of showing notification, throw a broadcast and add CustomAction via intent filter.
Now in the onReceive method of broadcast listener, check
if(intent.getAction.equals("CustomAction"))Intent i = new Intent(context, YourActivity);
context.startActivity(i);
Sorry for not a formatted answer, I'm driving, will update it later for more clarification.
Update
Register broadcast receiver in a sticky service. So that service can be started automatically if killed and register broadcast register again.
Don't forget to unregister broadcast receiver in onDestroy() method of service and also in YourActivity when you purpose is resolved.

Just adding a sticky service (which does nothing) fixed the issue. Adding the service prevented the process getting killed when user exits the app and removes it from recent app list.
Because of the service, the app process is running even when a no UI is visible. In this state, if an activity is shown from the GCM service, it gets shown.

You can trigger a broascast as Vinay mentioned. If it still does not work, try using wake-locks. These wake-locks help in waking the device when it is in sleep mode. It will act like force wake and after calling wake-locks, you can perform your actions.
Hope it helped..
Thanks.

When does Broadcast Receiver start?

I'm new to android and trying to build a simple app which needs to listen for incoming sms. I know that I need to use the BroadcastReceiver class and I also know how to make my own broadcast receiver. But how do I start it? Does it start automatically if I set the code for it in the manifest? The app just has the Main activity, do I need to somehow add a broadcast receiver in the onCreate of this activity? I searched for an answer, but it's still not clear to me. I know it's not nice to ask, but it would be great if you can share some sample code. Thanks!

If you declare the receiver within your AndroidManifest.xml, then you shouldn't need to do anything more. When a broadcast gets sent, the Android system will look through all installed apps and notify each app that has declared the appropriate Receiver in its manifest, starting the app in the process if necessary. For most cases, such as SMS, that is how you want to declare receivers, because most broadcasts are sent with the intent that you want to open your app when its not currently running to react to the broadcast.
Alternatively, you may declare the broadcast within a running activity, which may be useful if you want the broadcast to directly update the UI in your running app.
BroadcastReceiver Documentation

Own Broadcastreceiver didn't receive simulated SMS_RECEIVED

I'm currently working on a project where I analyze the SMS_RECEIVED-Flow.
According to the article [1] I simulated the SMS_RECEIVED-Broadcast with an explicit call to the service: com.android.mms.transaction.SmsReceiverService.
The problem is, that the Android-Emulator and my Nexus do forward
the generated BroadcastReceiver to the default SMS-App only and I do not know why.
I tried to catch the Broadcast with an statically registered receiver in another App and with an dynamically registered receiver (all receiver registered with the highest priority and the correct intent-filter). Both methods work fine with a normal SMS, but not with my simulated one.
So the question is, does anybody know how the SMS-Receive mechanism work and why my program won't receive any broadcasts.
[1] http://blog.dev001.net/post/14085892020/android-generate-incoming-sms-from-within-your-app

SmsRecieverService is part of default messaging app, so if you explicitly call this service, the broadcast will reach only that app. Since the SMS_RECIEVED broadcast is a protected broadcast , your app cannot broadcast it.
One way is to change the name of the broadcast in both simulator and your app.

Call a method from my "MainActivity" in Android

I'm currently messing up with the Google's C2DM notification service.
Following the steps in this tutorial: http://www.vogella.de/articles/AndroidCloudToDeviceMessaging/article.html, I succesfully recieved a "push message" from the server.
However, in the "protected void onMessage" I need to send the message to the "MainClass" to print it in a toast. Since I'm not deeply familiarized with the Android developing, I will appreciate any help on this. Thank you

Use a broadcast to communicate with the activity.
In onMessage send a broadcast.
In your activity onResume register a broadcast receiver and make it display a toast (remember to unregister it in the onPause)
You would need also to handle the case when the activity is not running (maybe display a notification). In this case, make the broadcast an ordered broadcast. The broadcast receiver in the activity should be set with a high prio, then register a default broadcast receiver through your manifest (this one displays a notification, or opens the activity, or whatever you want).