According to the instructions from Apple, to turn on iTunes Match on your iOS device (iPhone or iPad):
- On your iPhone, iPad, or iPod touch, tap Settings > Music.
- Turn on iTunes Match.
However, there seems to be a bug in iOS 7 whereby once you have subscribed to iTunes Match on your computer (you can’t subscribe from your iOS device, despite what the settings page seems to imply), instead of there being an option for ‘iTunes Match’, it will instead show a link to ‘Subscribe to iTunes Match’.
Clicking on the link will tell you that you have already subscribed to iTunes Match and then send you back to the settings page – not very helpful.
Luckily there seems to be a very simple solution.
- On your iPhone, iPad, or iPod touch, tap Settings > iTunes & App Store.
- Tap on the link where your Apple ID is displayed.
- Choose ‘Sign Out’ from the popup menu.
- Log back in using your Apple ID and password.
- Now you should see the option to turn on iTunes Match as per the screen shot below.