What does an app receive when you share something to it on an iPhone?

One parcel, and nothing else. iOS calls it an extension item: a small package of attachments, each tagged with its type, such as a web URL, an image, a piece of plain text, or a file. When you share a TikTok or an Instagram reel, what travels is almost always a single URL pointing at that public post. The receiving app does not get your account, your session, your feed, or the video file itself. It runs in its own process with its own sandbox, separate from the app you shared from, and it cannot reach back into it.

Why doesn't an app I installed show up in my iPhone share sheet?

Usually one of two reasons. The first is that the app declared which content types it accepts, and what you are sharing is not one of them. An app that registered only for web links will not appear when you share a photo, and that is intended behaviour rather than a bug. The second is placement: the share sheet shows a short list first and hides the rest. Swipe the app row to the end, tap More, then tap Edit, and toggle the app on. If it is still missing after that, restart the phone, and reinstall the app as a last step, because extensions occasionally fail to re-register with the system after an update.

Does sharing a video to an app give it access to my TikTok account?

No. A share extension receives only the item you handed it, which for a video post is a link to that public post. It has no access to your logged-in session, your feed, your saved posts, or your direct messages. iOS enforces that boundary at the process level rather than leaving it to the app to honour. What the receiving app can do is take that link and fetch the public post on its own servers, which is how a link becomes a product list. That is a real capability, and it is a long way from reading your account.

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What an app actually gets when you tap Share

September 3, 2026 · 6 min read

A clay-style vertical video card with a play button on it

When you tap Share and pick an app, iOS does not open that app. It hands it one small parcel and lets it work in a window over the top: usually a link, sometimes an image or a line of text, and nothing else. The video you were watching stays where it was. The app on the other side never learns which app the parcel came from.

That is the whole mechanism. It also explains most of the odd things the share sheet does, including why an app you definitely installed sometimes is not in the list, and why the privacy boundary runs in the opposite direction from the one people assume.

What actually travels

The parcel has a name. iOS calls it an extension item, and it carries a list of attachments, each one labelled with its type: a web URL, an image, plain text, a file. The label matters more than it sounds, because the receiving app reads the label first and decides what to do from there.

Share a TikTok to another app and what travels is one URL pointing at that public post. Often it arrives with a tail of tracking parameters on the end, the ones that look like “_t=” and “_r=1”. Those are TikTok's own share counters. They are noise. Any app reading the link keeps the video id and ignores the rest.

Here is what does not travel: your account, your logged-in session, your feed, your saved posts, and the video file itself. The receiving app gets an address, not the contents of the house. If it wants the post, it has to go and fetch the post, the same way anyone with the link could.

Why this beats copy and paste

Copying the link and pasting it works. It is also three more steps and one more failure point, and the failure point is the clipboard.

You never leave the video. The share extension opens over the app you are already in. Copy and paste makes you switch apps, find the field, and switch back.
The parcel is typed, a pasted string is not.The receiving app is told “this is a web URL”. A pasted line of characters has to be sniffed and guessed at, and a guess is a place where things go wrong.
No paste prompt.Since iOS 16, an app that reaches into the clipboard on its own has to ask permission first, which is the “Paste from Other Apps” alert. Sharing does not trigger it, because you handed the item over deliberately rather than the app going and taking it. Worth knowing that the prompt fires on the app reading the clipboard programmatically, not on you tapping Paste yourself.
The clipboard holds one thing. Copy a second link before you paste the first and the first is gone. Three videos means three round trips, in order, without getting distracted.

The boundary only runs one way

This is the part almost nobody explains, and it is backwards from the intuition.

A share extension runs as its own process with its own sandbox, separate from the app you shared from and separate even from its own parent app. It receives the parcel. It cannot read the app it was launched over. That much most people would guess correctly.

What people get wrong is the other direction. The app you shared from can be told which target you picked. The system passes the chosen destination back to the app that raised the share sheet, so it is able to know that you sent that post somewhere, and where. The receiving app has no matching signal in return. If a shopping app knows your link came from TikTok, it is because the URL says tiktok.com, not because iOS told it anything.

So the honest summary is: sharing tells the sender more than it tells the receiver. Neither of those is the same as account access. We wrote the longer version of this, including what we collect ourselves, in what shopping apps collect.

Why the app is missing from your share sheet

Two causes, and they need different fixes.

The content type does not match. Every share extension declares in advance what it accepts. An app registered for web links will not appear when you share a photo from your camera roll, and an app registered for images will not appear on a link. It is not broken and there is nothing to toggle. Share the other thing.

It is hidden behind More. Since iOS 26 the share sheet deliberately shows a shorter list up front, with the rest one swipe away. Swipe the app row to the end, tap More, then Edit. Toggle the app on, and drag the handles to reorder your favourites. Apps listed under Suggestions cannot be reordered, only switched on and off.

If neither works, restart the phone. Extensions sometimes fail to re-register after an app update, and a restart is the fix often enough to try before reinstalling.

Share the post, not the screenshot

For finding a product, this is the whole difference. A screenshot is one frame with the sound stripped off. The link is the entire post: what the creator said out loud, the caption, the on-screen text, the comments arguing underneath, and the creator's storefront one tap away. That is four more sources of evidence, and the shade name is usually in one of them rather than in the picture. The manual version of that hunt is fifteen minutes of tab-opening, which is exactly why the link is worth more than the frame.

The exception is a post that is private or already deleted. Then the link is an address with nothing behind it, and the screenshot you took is the only evidence that still exists. Share that instead. It is a worse starting point and it is better than nothing.

What we do with the parcel

Concretely, since being vague here would undercut the rest of the post. Stealsy's share extension receives the URL you handed it. It passes that URL to our servers, which fetch the public post and work out the products in it, then check every shop link by opening it before you ever see it. The extension does not read your feed, because it cannot. It does not know you were in TikTok, except that the link says so.

The limits, out loud: it is iPhone only, iOS 18 or later. Some posts have nothing identifiable in them and the honest output is a near match or a blank. And a private post stays private, because the server fetching it is not logged in as you.

Get Stealsy for iPhone — share a video, get the products, prices and verified links.

Common questions

What does an app receive when you share something to it on an iPhone?: One parcel, and nothing else. iOS calls it an extension item: a small package of attachments, each tagged with its type, such as a web URL, an image, a piece of plain text, or a file. When you share a TikTok or an Instagram reel, what travels is almost always a single URL pointing at that public post. The receiving app does not get your account, your session, your feed, or the video file itself. It runs in its own process with its own sandbox, separate from the app you shared from, and it cannot reach back into it.
Why doesn't an app I installed show up in my iPhone share sheet?: Usually one of two reasons. The first is that the app declared which content types it accepts, and what you are sharing is not one of them. An app that registered only for web links will not appear when you share a photo, and that is intended behaviour rather than a bug. The second is placement: the share sheet shows a short list first and hides the rest. Swipe the app row to the end, tap More, then tap Edit, and toggle the app on. If it is still missing after that, restart the phone, and reinstall the app as a last step, because extensions occasionally fail to re-register with the system after an update.
Does sharing a video to an app give it access to my TikTok account?: No. A share extension receives only the item you handed it, which for a video post is a link to that public post. It has no access to your logged-in session, your feed, your saved posts, or your direct messages. iOS enforces that boundary at the process level rather than leaving it to the app to honour. What the receiving app can do is take that link and fetch the public post on its own servers, which is how a link becomes a product list. That is a real capability, and it is a long way from reading your account.