Fix Android crash on push notification

android/app/src/main/java/com/mattermost/rnbeta/NotificationPreferences.java

@@ -0,0 +1,57 @@
+package com.mattermost.rnbeta;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+public class NotificationPreferences {
+    private static NotificationPreferences instance;
+
+    public final String SHARED_NAME = "NotificationPreferences";
+    public final String SOUND_PREF = "NotificationSound";
+    public final String VIBRATE_PREF = "NotificationVibrate";
+    public final String BLINK_PREF = "NotificationLights";
+
+    private SharedPreferences mSharedPreferences;
+
+    private NotificationPreferences(Context context) {
+        mSharedPreferences = context.getSharedPreferences(SHARED_NAME, Context.MODE_PRIVATE);
+    }
+
+    public static NotificationPreferences getInstance(Context context) {
+        if (instance == null) {
+            instance = new NotificationPreferences(context);
+        }
+
+        return instance;
+    }
+
+    public String getNotificationSound() {
+        return mSharedPreferences.getString(SOUND_PREF, null);
+    }
+
+    public boolean getShouldVibrate() {
+        return mSharedPreferences.getBoolean(VIBRATE_PREF, true);
+    }
+
+    public boolean getShouldBlink() {
+        return mSharedPreferences.getBoolean(BLINK_PREF, false);
+    }
+
+    public void setNotificationSound(String soundUri) {
+        SharedPreferences.Editor editor = mSharedPreferences.edit();
+        editor.putString(SOUND_PREF, soundUri);
+        editor.commit();
+    }
+
+    public void setShouldVibrate(boolean vibrate) {
+        SharedPreferences.Editor editor = mSharedPreferences.edit();
+        editor.putBoolean(VIBRATE_PREF, vibrate);
+        editor.commit();
+    }
+
+    public void setShouldBlink(boolean blink) {
+        SharedPreferences.Editor editor = mSharedPreferences.edit();
+        editor.putBoolean(BLINK_PREF, blink);
+        editor.commit();
+    }
+}