diff --git a/Yep/Activities.xcassets/wechat_session.imageset/Contents.json b/Yep/Activities.xcassets/wechat_session.imageset/Contents.json
index 95261f0c..8b3b2077 100644
--- a/Yep/Activities.xcassets/wechat_session.imageset/Contents.json
+++ b/Yep/Activities.xcassets/wechat_session.imageset/Contents.json
@@ -2,16 +2,7 @@
   "images" : [
     {
       "idiom" : "universal",
-      "scale" : "1x"
-    },
-    {
-      "idiom" : "universal",
-      "scale" : "2x",
-      "filename" : "wechat_session.png"
-    },
-    {
-      "idiom" : "universal",
-      "scale" : "3x"
+      "filename" : "wechat_session.pdf"
     }
   ],
   "info" : {
diff --git a/Yep/Activities.xcassets/wechat_session.imageset/wechat_session.pdf b/Yep/Activities.xcassets/wechat_session.imageset/wechat_session.pdf
new file mode 100644
index 00000000..9911e042
Binary files /dev/null and b/Yep/Activities.xcassets/wechat_session.imageset/wechat_session.pdf differ
diff --git a/Yep/Activities.xcassets/wechat_timeline.imageset/Contents.json b/Yep/Activities.xcassets/wechat_timeline.imageset/Contents.json
index 62fc7b11..8ef2ebbc 100644
--- a/Yep/Activities.xcassets/wechat_timeline.imageset/Contents.json
+++ b/Yep/Activities.xcassets/wechat_timeline.imageset/Contents.json
@@ -2,16 +2,7 @@
   "images" : [
     {
       "idiom" : "universal",
-      "scale" : "1x"
-    },
-    {
-      "idiom" : "universal",
-      "scale" : "2x",
-      "filename" : "wechat_timeline.png"
-    },
-    {
-      "idiom" : "universal",
-      "scale" : "3x"
+      "filename" : "wechat_timeline.pdf"
     }
   ],
   "info" : {
diff --git a/Yep/Activities.xcassets/wechat_timeline.imageset/wechat_timeline.pdf b/Yep/Activities.xcassets/wechat_timeline.imageset/wechat_timeline.pdf
new file mode 100644
index 00000000..0b05a558
Binary files /dev/null and b/Yep/Activities.xcassets/wechat_timeline.imageset/wechat_timeline.pdf differ
diff --git a/Yep/Activities.xcassets/wechat_timeline.imageset/wechat_timeline.png b/Yep/Activities.xcassets/wechat_timeline.imageset/wechat_timeline.png
deleted file mode 100644
index 8a38eaa1..00000000
Binary files a/Yep/Activities.xcassets/wechat_timeline.imageset/wechat_timeline.png and /dev/null differ