Q: What I want from iTunes Match, and what was possible in iOS 5 is to enable the feature to show all my music in the cloud and download what I want to listen to and then disable show all my music and just use and see the music which is on my iPhone. I don’t want to stream because of my data plan and some “blank spots” in my 3G. What was Apple thinking when they created this “new feature”? The whole world has the same access to internet as Apple does in San Francisco, and they should let the people stream?
– Dave, in a comment on Can’t remove iTunes Match tracks in iOS 6

A: There appears to be a lot of confusion about the streaming versus downloading aspects of iTunes Match. This seems to be partially due to cosmetic changes that Apple made to the Music app user interface in iOS 6 along with some erroneous reports that have been circulating on the Internet dating back to the early iOS 6 betas suggesting that Apple was moving to a predominantly streaming approach.
The bottom line, however, is that little has actually changed in iOS 6, and iTunes Match and the iOS Music app continues to basically work as it did before when it comes to playing back content. In short, iTunes Match does not “stream” music in the sense that most services define “streaming.”. The iOS Music app always downloads music, regardless of whether you do specifically or simply listen to it.
When you begin playing a track on an iPhone, iPod touch or iPad, the device will check to see if it already has that track stored locally. If so, the local copy is used; otherwise iTunes Match begins downloading the track from iCloud, beginning playback as soon as enough of the track has been downloaded to ensure an uninterrupted experience—usually within a second or two.
The practical upshot of this is that once you’ve listened to any track once, it remains on your device, so bandwidth usage is not really a crucial concern. Listening to a track once will cause it to be downloaded to your device and that locally stored copy will be used the next time you play the track back. In fact, simply listening to one of your favourite albums or playlists once through will have the same effect as downloading it manually—each of those tracks will be downloaded and stored on your device as they are played, and will remain on your device for the next time you listen to that playlist.
The option also still remains in iOS 6 to pre-download entire playlists or albums, however. The only major difference in this regard from iOS 5 is that individual tracks can no longer be specifically downloaded on-demand. Simply playing an individual track will download and retain a local copy of it, however, and most users pre-downloading content are likely working from albums or playlists anyway in much the same way as they would have when syncing music from iTunes.
Keep in mind, however, that iOS considers your iTunes Match music to be volatile in the sense that it will start purging content should you be running low on space on the device. In this case, manually downloaded content appears to take priority over automatically downloaded content, and iOS tries to purge tracks on a first-in-first-out basis, meaning the least recently-downloaded tracks will be removed first.
Note also that if you are on a limited cellular data plan, you can easily turn OFF downloading of iTunes Match content via your cellular data connection by going to the Music options in the Settings app and toggling off the Use Cellular Data option.
When no valid data connection is available for iTunes Match—either because you are out of coverage entirely or you have the Use Cellular Data option disabled and are not on a Wi-Fi connection—any tracks that are not stored locally on your device will appear greyed out, indicating that they are not available for playback. In iOS 5 attempting to select one of these tracks would present an error message indicating that the track is not available for playback without an appropriate data connection; in iOS 6 these tracks simply cannot be selected at all and will be silently skipped over during playback. The upshot is that you won’t risk inadvertently playing back these tracks and using up cellular data bandwidth, although you still have the option of temporarily toggling Use Cellular Data back on if you find that there’s a specific track that you really want to listen to and can’t wait until you get back onto a Wi-Fi connection.
In addition, the Show All Music option remains available under the Music settings as it did in iOS 5, and toggling this option OFF will have the same effect as before—music not already downloaded onto your device will be hidden entirely. Again, however, this includes both music you’ve specifically downloaded (by playlist or album), as well as any tracks that you’ve simply listened to from the cloud.
The only major change in iOS 6 is the inability to easily delete music that you no longer want on your device. iOS 6 is supposed to handle this for you if it needs the space for something else, although in our own testing this appears to not yet be fully polished; we have seen out of space errors pop up when attempting to download large apps or videos on a constrained device and only somewhat later does iOS decide to purge iTunes Match content to make room for the new content. This seems to be based somewhat on the actual available space on the device, as opposed to the size of a new item that you are attempting to download; in other words, an iPhone with under 1GB of free space will be more likely to purge iTunes Match content automatically, as opposed to attempting to download a 4GB video on a device that only has 2GB free. This also seems to be more of an issue when actually downloading new content as opposed to filling space more gradually, such as when taking photos or recording video.