How to generate App Store screenshots in GitHub Actions

Steps

1. 1

   Create an API key and store it as a secret

   Generate a key from your account, then add it under Settings, Secrets and variables, Actions as APPSCREENSHOT_API_KEY.

   Every request authenticates with a bearer token against https://appscreenshotstudio.com/api/v1:

   Authorization: Bearer sk_live_your_key_here
   

   Never inline the key in the workflow file. A workflow file is readable by anyone who can read the repository.

2. 2

   Create a project

   A project holds the device target and the canvas. Create one per run, or reuse a fixed project id if you want the same canvas updated each time.

   curl -sS -X POST https://appscreenshotstudio.com/api/v1/projects \
     -H "Authorization: Bearer $APPSCREENSHOT_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "device_id": "iphone-6.9",
       "name": "Release screenshots"
     }'
   

   The response carries the project id under data.id.

3. 3

   Generate the set from a description

   The chat endpoint takes natural language and composes the cards. This is the step that costs credits, so keep it to one call per run rather than one per card.

   curl -sS -X POST "https://appscreenshotstudio.com/api/v1/projects/$PROJECT_ID/chat" \
     -H "Authorization: Bearer $APPSCREENSHOT_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "message": "A habit tracking app for people who keep abandoning streaks. Dark UI, emerald accents. Five cards: the streak view, adding a habit, the weekly chart, reminders, and the widget."
     }'
   

4. 4

   Render and collect the files

   Rendering costs no credits. The response returns one entry per card with a URL and its pixel size.

   curl -sS -X POST "https://appscreenshotstudio.com/api/v1/projects/$PROJECT_ID/render" \
     -H "Authorization: Bearer $APPSCREENSHOT_API_KEY" \
     | jq -r '.data.images[].url' \
     | xargs -n1 -I{} curl -sS -O {}
   

   The shape it returns:

   {
     "success": true,
     "data": {
       "images": [
         { "card_index": 0, "url": "https://...png", "width": 1260, "height": 2736 }
       ]
     }
   }
   

5. 5

   Flatten before these files reach App Store Connect

   The render endpoint returns PNG. A PNG written from a canvas carries an alpha channel even when every pixel is opaque, and App Store Connect refuses files that carry one.

   Add a flattening step in the job rather than discovering it at submission:

   sudo apt-get install -y imagemagick
   for f in *.png; do
     magick "$f" -background white -alpha remove -alpha off -quality 95 "${f%.png}.jpg"
   done
   

   The alpha channel page covers what the error looks like when it does reach you.

6. 6

   Publish them as artifacts

   Putting the whole thing together as a workflow:

   name: Screenshots
   on:
     workflow_dispatch:
   
   jobs:
     generate:
       runs-on: ubuntu-latest
       env:
         API: https://appscreenshotstudio.com/api/v1
         KEY: ${{ secrets.APPSCREENSHOT_API_KEY }}
       steps:
         - name: Create project
           run: |
             PROJECT_ID=$(curl -sS -X POST "$API/projects" \
               -H "Authorization: Bearer $KEY" \
               -H "Content-Type: application/json" \
               -d '{"device_id":"iphone-6.9","name":"CI run"}' | jq -r '.data.id')
             echo "PROJECT_ID=$PROJECT_ID" >> "$GITHUB_ENV"
   
         - name: Generate
           run: |
             curl -sS -X POST "$API/projects/$PROJECT_ID/chat" \
               -H "Authorization: Bearer $KEY" \
               -H "Content-Type: application/json" \
               -d '{"message":"A habit tracking app. Dark UI, emerald accents. Five cards."}'
   
         - name: Render and download
           run: |
             curl -sS -X POST "$API/projects/$PROJECT_ID/render" \
               -H "Authorization: Bearer $KEY" \
               | jq -r '.data.images[].url' | xargs -n1 -I{} curl -sS -O {}
   
         - name: Flatten for App Store Connect
           run: |
             sudo apt-get install -y imagemagick
             for f in *.png; do
               magick "$f" -background white -alpha remove -alpha off -quality 95 "${f%.png}.jpg"
             done
   
         - uses: actions/upload-artifact@v4
           with:
             name: app-store-screenshots
             path: "*.jpg"