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Run through this checklist once per iPhone, in order, before you install the runner. The one you cannot skip is UI Automation (Settings → Developer): without it, Warmr can’t drive the phone and nothing runs at all. Two more, Appearance = Light and StandBy = Off, are the most common reason a set-up iPhone looks like it’s hanging. Do all three and you’ll avoid the majority of first-run problems.
The three that matter most. Turn UI Automation On (Settings → Developer) — without it nothing runs at all. Set Appearance to Light (not Dark, not Automatic) and turn StandBy Off — skip either and sessions stall silently with no obvious error.

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The settings, in order

1

Developer Mode = On

Settings → Privacy & Security → Developer Mode → On. The iPhone prompts to restart. Confirm. After it reboots, unlock the phone and confirm Developer Mode again at the second prompt.Why: required on iOS 17+. Without Developer Mode, iOS refuses to launch the runner (which is signed with a development certificate).
If Developer Mode isn’t in Privacy & Security, the option only appears after the iPhone has been connected to a Mac running Xcode at least once. Connect it to your Mac, then re-check.
2

Enable UI Automation (required)

Settings → scroll to the very bottom → Developer → Enable UI Automation → On. The Developer menu only appears at the bottom of Settings once Developer Mode (above) is on.Why: this is the switch that lets the runner actually drive the phone. Without UI Automation, Warmr cannot tap or type and no session runs at all — the Mac connects, but every automation attempt fails (this is the cause of the Code 41 error). It’s the single most-skipped step, so don’t move on until it’s on.
3

Trust the Mac

Plug the iPhone into the Mac. When Trust This Computer? appears, tap Trust and enter the passcode. If the prompt never appears, the device is already trusted. That’s fine.
4

Auto-Lock = Never

Settings → Display & Brightness → Auto-Lock → Never (or at least 5 minutes).Why: a locked screen pauses automation. Never is simplest for a device that stays on your desk.
5

Brightness ≥ 50%

Settings → Display & Brightness: set the slider to the middle or higher.Why: Warmr reads the screen to find tap targets. A very dim screen makes that less reliable.
6

Appearance = Light (required)

Settings → Display & Brightness → Appearance → Light.Why: on Dark appearance some app screens render in near-black, and Warmr can’t reliably find on-screen targets. Uploads stall. Automatic is just as bad because it flips to Dark at night and breaks scheduled sessions. Use Light.
7

Disable iCloud Photos

Settings → Photos → iCloud Photos → Off.Why: keeps the iPhone’s gallery limited to the content you staged for posting. Otherwise photos from your iCloud library can sync down and accidentally end up in a post.
8

StandBy = Off (required)

Settings → StandBy → Off.Why: StandBy is the iOS 17+ feature that turns a charging iPhone into a desk clock when it’s lying on its side. It kicks in after ~30 seconds when the device is charging + horizontal + locked + idle: exactly the state a desk iPhone sits in. Once StandBy is active, iOS blocks app launches, so Warmr can’t open the app and the session stalls.
Less-reliable alternative: keep the iPhone upright while charging (a stand works). StandBy only activates lying flat. Portrait Orientation Lock does not help; StandBy reads the accelerometer directly. Turning StandBy off is the clean fix and changes nothing else on the phone.
9

Reduce Motion = On (optional)

Settings → Accessibility → Motion → Reduce Motion → On.Why: disables animated transitions, which makes screens settle faster and slightly more reliable to read. Optional, but recommended.
10

Install the platform app and log in

Install the app you’ll be warming (for example, TikTok) from the App Store, open it, and sign into the account. The account must be logged in on the device before Warmr can warm or post it.

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Per-iPhone checklist

Use this as a quick pass before installing the runner:
  • Developer Mode = On
  • UI Automation = On (Settings → Developer)
  • Trusted this Mac
  • Auto-Lock = Never (or ≥ 5 minutes)
  • Brightness ≥ 50%
  • Appearance = Light (not Dark, not Automatic)
  • iCloud Photos = Off
  • StandBy = Off
  • Reduce Motion = On (optional)
  • Platform app installed and logged in
Setting up several iPhones? Run the whole checklist on one device first and confirm a warmup works end to end before repeating it across the rack. It’s faster to catch a missed setting once than ten times.
Settings done? Next, install the runner on each iPhone.