Does a Download Keep Going When You Lock Your Phone?

Sometimes. A transfer the system is carrying for an app, the kind Safari and the App Store use, keeps running while your screen is locked. A transfer running inside an app usually stalls within seconds of that app leaving the screen. Force-quitting ends both. Which one you have is a property of the app, not of the file.

Two kinds of download, one word for both

Some apps register a transfer with iOS and step back. The system owns it from there, moves the bytes on its own schedule, and wakes the app when there is a finished file to collect. This is why an App Store update lands while your phone sits face down on a table.

Other apps read the bytes themselves as they arrive. Nothing is delegated, so nothing continues without the app. Both are called downloading and look identical from the outside, which is why the same question gets opposite answers.

What locking the screen actually does

Locking is not a pause. To the app it is the same event as switching to another app: it leaves the screen, gets a short grace period measured in seconds, and is then suspended. A suspended app is still in memory but receives nothing, so an in-process transfer stops advancing until you come back.

What you do	System-carried transfer	In-app transfer
Lock the screen	Continues	Stalls after a few seconds
Switch to another app	Continues	Stalls after a few seconds
Come back to the app	Already further along	Resumes or restarts
Swipe the app away	Cancelled	Cancelled

Low Power Mode sits underneath all of it, throttling background work, so a transfer you assumed ran overnight may have idled instead.

The silence before the first byte

Long videos add their own confusion. A source that only exists as thousands of small streaming segments has to be assembled into one finished MP4 before a single byte can be sent to your phone, and during that assembly the progress bar has nothing to report. Minutes of apparent nothing is the work happening somewhere else rather than a stall, and leaving the app during that window is what actually kills it. If it fails outright rather than sitting quiet, the usual reasons are worth a look.

Why a vault app keeps the transfer in the app

Handing a download to the system costs something a privacy app cannot pay. The system writes the incoming file to a staging location of its own, in the clear, outside anything the app encrypts. For a photo vault that is the whole promise gone for the length of a download.

So Arca streams the bytes itself into a file it creates with protection already on, and accepts the trade: for a long video, keep the app on screen. In practice that means

• start long saves on Wi-Fi with Arca open, and short clips wherever you like, since most finish before the question matters
• expect an hour of video to take real time, especially from longer YouTube uploads
• never swipe the app away to hurry it along
• paste the link again if it died while you were elsewhere, because the partial file is deleted rather than kept

Where Arca fits

What arrives is encrypted on the way in: AES-256-GCM with an Argon2id-derived key, no automatic vault upload or Arca account, and no trip through your photo library. That protects the file once it is in the vault. It does not change what the platform you took it from allows, and it makes no claim about anything you saved somewhere else first. Save what you have the right to save — your own uploads, content a platform offers for download, public posts kept for personal offline use — and remember that the platform’s terms still apply to you.

Get Arca on the App Store