I’ve been having major issues with my iPhone 6 running out of storage capacity. I have a modest amount of apps installed on the iPhone & I have the 16GB version of the iPhone 6. I was constantly receiving the storage almost full banner on my iPhone and even when looking at the storage & iCloud usage in settings I couldn’t figure out what was taking up all the space. This tutorial will also apply to iPad as it’s an iOS issue and not an iPhone specific issue. Works well if you keep receiving the message “iphone storage full” and you use iTunes match or iCloud Music Library
I first tried deleting old apps and app data. This helped a little. I then deleted all of the music off my device which freed up some space but not a great deal. Next I opened the Battery Doctor app and ran the clean up scripts included, which clean out old cache and orphaned files. Again, this gave me a few extra MB but nothing noticeable.
The final thing I tried was to disable iCloud music under settings > music. As soon as I returned to check the storage space available I could see I had quite a bit more free. I checked back 5 minutes later and I had gone from almost full to 2GB free. It would seem that the caching of music on the iPhone with iTunes match is very inefficient on smaller devices. I see the benefit of caching music files for quicker retrieval & a reduction in cellular usage, but on smaller devices this really doesn’t help and I do wish they would include a way to disable caching, or a cache time-out.
If you use an Apple iPhone or iPad along with iTunes match/iCloud music I would advise giving this trick a go. Turn off iCloud music and watch your free space return. I now do this on a regular basis to free up space & delete the cache. It has really helped me free up space & made my 16GB iPhone much more useable.
If you are having the same issue please do let me know. I would love to hear your own fixes for storage issues on smaller iOS devices. iTunes match & iCloud music library seem very under-optimised in iOS 9 & I do hope they invest some more time & effort into improving this, especially on 16GB devices which I assume they will phase out in future iPhone & iPad models.