iOS/OSX app relaunch persistent playlist entries

First time post here, 25 yr DSP guy, 9 month JUCE user. After creating a playlist (URL) entry and play the associated audio file, everything is fine. When the app is closed then reopened, selecting the file in the playlist crashes the app on iOS and on OSX I have a dialog popup to say that the file is invalid. All this is probably due to persistent file permissions/security scoped bookmarks (it works ok on windows and Android). Anyone have a quick example of how to make the apple URL’s persistent between app launches? Thanks.