Reasons
2.16: Multitasking Apps may only use background services for their intended purposes: VoIP, audio playback, location, task completion, local notifications, etc. 17.5: Apps that include account registration or access a user’s existing account must include a privacy policy or they will be rejected ----- 2.16 -----
We found that your app uses a background mode but does not include functionality that requires that mode to run persistently. This behavior is not in compliance with the App Store Review Guidelines.
We noticed your app declares support for location in the UIBackgroundModes key in your Info.plist but does not include features that require persistent location. specifically, it would be appropriate to revise your app to use significant-change location services to achieve the functionality you have described.
Since your application does not require persistent, real-time location updates, we recommend using the significant-change location service or the region monitoring location service.
For more information on these options, please see the "Starting the Significant-Change Location Service" and "Monitoring Shape-Based Regions" sections in the Location Awareness Programming Guide.
If you choose to add features that use the Location Background Mode, please include the following battery use disclaimer in your Application Description:
"Continued use of GPS running in the background can dramatically decrease battery life."
----- 17.5 -----
We also noticed that your app includes account registration or access to users’ existing accounts but does not include a privacy policy, which does not comply with the App Store Review Guidelines.
Please update your app metadata to include a privacy policy and ensure that the privacy policy URL you provide directs the user to the intended destination.
If your iTunes Connect Application State is Rejected, a new binary will be required. Make the desired metadata changes when you upload the new binary.
NOTE: Please be sure to make any metadata changes to all App Localizations by selecting each specific localization and making appropriate changes.
For discrete code-level questions, you may wish to consult with Apple Developer Technical Support. When the DTS engineer follows up with you, please be ready to provide:
1. In 2.16 what are the thing I need to do before re-submitting the app to store?
2. Currently I have included the privacy policy in it, even though they rejected, any clue?
For 2.16 As per, App Store Review Guidelines I can say that you are using Location Service or any another service in background which is not consistently used in app. So why to put load in background process? Decide your flow and based on that use those services on pro-active basis. Do not run or use any background services. Sometime background process stops automatically by malfunctioning of other app or memory related issues. e.g. Let's say I want to use GPS for location based service. Why should i invoke the service call until I want Longitude and Latitude by writing it in background services? I am using it whenever I need the GPS data.
For 17.5, I guess you have uploaded Privacy Policy so it's fine. So,make the change accordingly and upload the build again. Best of luck.
Need to Specify the Key in plist for the Backgroundmode. Example If you are tracking users location in foreground and used backgroundmode in capabilities then your app may get rejected in binary testing. Make sure that you use Both the functionalities and Plist key for the background which you are using.
I've thoroughly reviewed the reason for 2.16 mentioned above - which looks similar to what we had for one of our apps.
In our scenario - it was meta data rejected. We simply added this line at the end of the description. Disclaimer: Continued use of GPS running in the background can dramatically decrease battery life.
If in you case - if you were asked to upload a new binary. Along with above line also follow the above suggestions for modifying UIBackgroundModes and ensure how that will effect your app feature.
For 17.5 - app should be accessible with very limited information to register - instead of lengthy fields - and more over it should clearly mention which field is mandatory and optional. Please mention why you need such information in privacy policy. Also review some sample privacy policies of other apps what they have included.
Hope this answer helps someone. Happy coding.
来源：https://stackoverflow.com/questions/26032995/apple-store-rejected-ios-application-due-to-background-modes