diff --git a/twidere/src/google/kotlin/org/mariotaku/twidere/util/MapFragmentFactoryImpl.kt b/twidere/src/google/kotlin/org/mariotaku/twidere/util/MapFragmentFactoryImpl.kt
index 3205bd739..37ff902b7 100644
--- a/twidere/src/google/kotlin/org/mariotaku/twidere/util/MapFragmentFactoryImpl.kt
+++ b/twidere/src/google/kotlin/org/mariotaku/twidere/util/MapFragmentFactoryImpl.kt
@@ -32,7 +32,8 @@ import org.mariotaku.twidere.fragment.WebMapFragment
  * Created by mariotaku on 15/4/27.
  */
 class MapFragmentFactoryImpl : MapFragmentFactory() {
-    override fun createMapFragment(context: Context): Fragment? {
+
+    override fun createMapFragment(context: Context): Fragment {
         if (GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(context) == ConnectionResult.SUCCESS) {
             return GoogleMapFragment()
         }
diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/constant/PreferenceKeys.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/constant/PreferenceKeys.kt
new file mode 100644
index 000000000..af5189127
--- /dev/null
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/constant/PreferenceKeys.kt
@@ -0,0 +1,65 @@
+package org.mariotaku.twidere.constant
+
+import android.content.SharedPreferences
+import android.os.Build
+import android.text.TextUtils
+import org.mariotaku.kpreferences.*
+import org.mariotaku.twidere.TwidereConstants.*
+import org.mariotaku.twidere.extension.getNonEmptyString
+import org.mariotaku.twidere.model.CustomAPIConfig
+import org.mariotaku.twidere.model.ParcelableCredentials
+
+/**
+ * Created by mariotaku on 16/8/25.
+ */
+
+val mediaPreviewStyleKey = KStringKey(KEY_MEDIA_PREVIEW_STYLE, VALUE_MEDIA_PREVIEW_STYLE_CROP)
+val profileImageStyleKey = KStringKey(KEY_PROFILE_IMAGE_STYLE, VALUE_PROFILE_IMAGE_STYLE_ROUND)
+val textSizeKey = KIntKey(KEY_TEXT_SIZE, 15)
+val nameFirstKey = KBooleanKey(KEY_NAME_FIRST, true)
+val displayProfileImageKey = KBooleanKey(KEY_DISPLAY_PROFILE_IMAGE, true)
+val mediaPreviewKey = KBooleanKey(KEY_MEDIA_PREVIEW, true)
+val bandwidthSavingModeKey = KBooleanKey(KEY_BANDWIDTH_SAVING_MODE, false)
+val displaySensitiveContentsKey = KBooleanKey(KEY_DISPLAY_SENSITIVE_CONTENTS, false)
+val hideCardActionsKey = KBooleanKey(KEY_HIDE_CARD_ACTIONS, false)
+val iWantMyStarsBackKey = KBooleanKey(KEY_I_WANT_MY_STARS_BACK, false)
+val showAbsoluteTimeKey = KBooleanKey(KEY_SHOW_ABSOLUTE_TIME, false)
+val linkHighlightOptionKey = KStringKey(KEY_LINK_HIGHLIGHT_OPTION, VALUE_LINK_HIGHLIGHT_OPTION_NONE)
+val statusShortenerKey = KNullableStringKey(KEY_STATUS_SHORTENER, null)
+val mediaUploaderKey = KNullableStringKey(KEY_MEDIA_UPLOADER, null)
+val newDocumentApiKey = KBooleanKey(KEY_NEW_DOCUMENT_API, Build.VERSION.SDK_INT == Build.VERSION_CODES.M)
+val loadItemLimitKey: KIntKey = KIntKey(KEY_LOAD_ITEM_LIMIT, DEFAULT_LOAD_ITEM_LIMIT)
+
+object defaultAPIConfigKey : KPreferenceKey<CustomAPIConfig> {
+    override fun contains(preferences: SharedPreferences): Boolean {
+        if (preferences.getString(KEY_API_URL_FORMAT, null) == null) return false
+        return true
+    }
+
+    override fun read(preferences: SharedPreferences): CustomAPIConfig {
+        val apiUrlFormat = preferences.getNonEmptyString(KEY_API_URL_FORMAT, DEFAULT_TWITTER_API_URL_FORMAT)
+        val authType = preferences.getInt(KEY_AUTH_TYPE, ParcelableCredentials.AuthType.OAUTH)
+        val sameOAuthSigningUrl = preferences.getBoolean(KEY_SAME_OAUTH_SIGNING_URL, false)
+        val noVersionSuffix = preferences.getBoolean(KEY_NO_VERSION_SUFFIX, false)
+        val consumerKey = preferences.getNonEmptyString(KEY_CONSUMER_KEY, TWITTER_CONSUMER_KEY).trim()
+        val consumerSecret = preferences.getNonEmptyString(KEY_CONSUMER_SECRET, TWITTER_CONSUMER_SECRET).trim()
+        return CustomAPIConfig("Default", apiUrlFormat, authType, sameOAuthSigningUrl,
+                noVersionSuffix, consumerKey, consumerSecret)
+    }
+
+    override fun write(editor: SharedPreferences.Editor, value: CustomAPIConfig): Boolean {
+        if (!TextUtils.isEmpty(value.consumerKey) && !TextUtils.isEmpty(value.consumerSecret)) {
+            editor.putString(KEY_CONSUMER_KEY, value.consumerKey)
+            editor.putString(KEY_CONSUMER_SECRET, value.consumerSecret)
+        } else {
+            editor.remove(KEY_CONSUMER_KEY)
+            editor.remove(KEY_CONSUMER_SECRET)
+        }
+        editor.putString(KEY_API_URL_FORMAT, value.apiUrlFormat)
+        editor.putInt(KEY_AUTH_TYPE, value.authType)
+        editor.putBoolean(KEY_SAME_OAUTH_SIGNING_URL, value.isSameOAuthUrl)
+        editor.putBoolean(KEY_NO_VERSION_SUFFIX, value.isNoVersionSuffix)
+        return true
+    }
+
+}
\ No newline at end of file
diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/extension/SharedPreferencesExtensions.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/extension/SharedPreferencesExtensions.kt
new file mode 100644
index 000000000..976a73ff1
--- /dev/null
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/extension/SharedPreferencesExtensions.kt
@@ -0,0 +1,12 @@
+package org.mariotaku.twidere.extension
+
+import android.content.SharedPreferences
+import android.text.TextUtils
+
+/**
+ * Created by mariotaku on 16/8/25.
+ */
+fun SharedPreferences.getNonEmptyString(key: String, def: String): String {
+    val v = getString(key, def)
+    return if (TextUtils.isEmpty(v)) def else v
+}
\ No newline at end of file