How to open an M3U file on iPhone

An M3U file is a list of stream addresses, not a video, so tapping one doesn't play anything. It needs a player that reads the list. Here's how to get a link or a file into one, with Vela as the example; Vela includes no channels, so the list comes from a service you use.

What's in an M3U file

M3U is plain text: a first line that may name a TV guide, then, for each entry, a line of details followed by the stream's address.

#EXTM3U url-tvg="http://example.com/epg.xml.gz"
#EXTINF:-1 tvg-id="news.example" group-title="News",Example News
http://example.com/live/1001.ts

M3U8 is the same format saved as UTF-8 text, which keeps names in any alphabet intact. The same ending is also used by HLS, Apple's streaming format, where one .m3u8 address is a single stream rather than a list of channels. You can tell them apart in a text editor: an HLS stream has lines starting #EXT-X-, and a channel list has a channel's name at the end of each #EXTINF line.

What happens when you tap one

A link in Safari: depending on how the server sends it, Safari shows the list as text, asks whether to download it, or opens its video player, which can't play a channel list. A single HLS stream is different: Safari plays that itself.
A file in Files or Mail: iOS shows a preview if it can, or just the file's name and size. It has no player for channel lists of its own.

Nothing is broken either way. A channel list is a set of addresses, not a video, and it needs a player that reads the list, either by fetching the link itself or from a copy of the file.

Getting the file into Files

From Mail: open the attachment, tap the share button and choose Save to Files.
From Safari: when Safari asks, tap Download. The file goes to the Downloads folder in Files, which is in iCloud Drive unless you've changed it in Safari's settings.
From a computer: put it in iCloud Drive, and it appears in Files on the iPhone.

Either iCloud Drive or On My iPhone will do, as long as you can find the file again.

A link or a file?

A link is fetched again each time the player refreshes, so changes to the list arrive by themselves. If your provider gave you a link, use it.
A file is a snapshot. Vela keeps its own copy and reads that again on refresh, but nothing new arrives until you import a newer file.
A get.php link with a username and password in it is really an Xtream login, which brings film details and a guide for each channel. See M3U playlist or Xtream login.

Opening a link in Vela

Install Vela from the App Store and open it. If you already use it, go to Account and tap Add a provider.
Choose M3U Playlist.
Paste the address into Playlist Link (M3U or M3U8). Vela reads the start of the list straight away, and if its first line names a guide, fills in TV Guide Link (XMLTV, optional) for you.
Add a Name (optional) if you like, and tap Sign In.

If the link is a get.php link with a login inside, Vela says so and signs in with the login. To read it as a list instead, turn on Read it as a plain playlist instead.

Opening a file in Vela

Choose M3U Playlist (in Account, tap Add a provider first if you already use Vela).
If you have a separate guide link, paste it into TV Guide Link (XMLTV, optional) first. Leave it empty and Vela uses the guide the file names in its first line, if it names one.
Tap Import from Files, find the file under Recents, iCloud Drive or On My iPhone, and tap it.

Vela copies the file and reads it there and then. The provider takes the file's name unless you typed one, and Account shows its playlist as Imported file. Vela goes by what's inside rather than the ending, so a playlist saved as .txt, with no ending, or gzipped, opens too.

One thing Vela doesn't do: offer itself when you tap an M3U file in Files or Mail. Start from Import from Files in Vela instead.

Entries on addresses other than http:// and https://, such as udp:// or rtmp://, are left out, and the Playlist section in Account says how many were.

If it doesn't open

“That does not look like an M3U playlist.” The file or link holds something else. Open it in a text editor to see what.
“That link returned a web page, not a playlist. Check the address, and that it does not need you to sign in in a browser first.” The link is wrong, has expired, or leads to a sign-in page.
“That playlist is empty.” There's nothing in it right now.
“That link could not be read. It should start with http:// or https://.”
“The imported playlist file is missing. Remove this provider and import it again.”

More in IPTV not working on iPhone, and for a guide that stays empty, XMLTV and EPG links.

Vela includes no channels or content. Use it only with a subscription or playlist you're entitled to use.