From iOS 8 and above, you can upload files to inSync Share directly from third-party apps. 

To upload files directly

1. Open the third-party app from from which you want to upload files to inSync Share.
2. Select the file that you want to upload. 
3. Open inSync using the export file options that are availble in the third-party app. The Mobile Uploads folder of inSync Share is displayed. You can choose a different location in inSync Share by tapping the Mobile Uploads folder name. Navigate to the desierd folder and select Choose.
4. After choosing the desired lcoation, tap Save to upload the file. A Upload Completed message is displayed.