Fastlane Screenshot Automation

This skill provides expert knowledge on using Fastlane for automated screenshot generation and app store deployment for iOS and Android apps.

When to Use

• Setting up Fastlane for screenshot automation
• Configuring fastlane snapshot for iOS simulators
• Configuring fastlane screengrab for Android emulators
• Managing device/simulator configurations for different screen sizes
• Generating localised screenshots
• Automating app store submissions

Fastlane Overview

Fastlane is a suite of tools for automating mobile app development workflows:

Tool	Platform	Purpose
snapshot	iOS	Automated screenshots
screengrab	Android	Automated screenshots
frameit	Both	Add device frames to screenshots
deliver	iOS	Upload to App Store Connect
supply	Android	Upload to Play Console
match	iOS	Code signing management
pilot	iOS	TestFlight management

Installation

Via Homebrew (Recommended)

brew install fastlane

Via RubyGems

sudo gem install fastlane -NV

Verify Installation

fastlane --version

Project Setup

Initialise Fastlane

# In your project root
fastlane init

This creates:

• fastlane/Fastfile - Lane definitions
• fastlane/Appfile - App configuration

Directory Structure

your-project/
├── ios/
│   └── fastlane/
│       ├── Fastfile
│       ├── Appfile
│       ├── Snapfile
│       └── screenshots/
├── android/
│   └── fastlane/
│       ├── Fastfile
│       ├── Appfile
│       ├── Screengrabfile
│       └── screenshots/
└── ...

iOS Screenshot Automation (Snapshot)

Initialise Snapshot

cd ios
fastlane snapshot init

Creates:

• fastlane/Snapfile - Snapshot configuration
• fastlane/SnapshotHelper.swift - UI test helper

Snapfile Configuration

# fastlane/Snapfile

# Simulators to use for screenshots
devices([
  "iPhone 15 Pro Max",    # 6.7" display
  "iPhone 14 Plus",       # 6.5" display
  "iPhone 8 Plus",        # 5.5" display
  "iPad Pro (12.9-inch) (6th generation)"  # If iPad support
])

# Languages for localised screenshots
languages([
  "en-GB",
  "en-US",
  "de-DE",
  "fr-FR",
  "ja",
  "zh-Hans"
])

# Output directory
output_directory("./fastlane/screenshots")

# Clear previous screenshots
clear_previous_screenshots(true)

# Xcode scheme (must have UI tests)
scheme("YourAppUITests")

# Workspace (for CocoaPods projects)
workspace("../YourApp.xcworkspace")

# Or project (if not using CocoaPods)
# project("../YourApp.xcodeproj")

# Override status bar (clean screenshots)
override_status_bar(true)

# Launch arguments (optional)
launch_arguments(["-screenshots"])

# Number of concurrent simulators
concurrent_simulators(true)

# Stop on first error
stop_after_first_error(false)

# Skip opening HTML summary
skip_open_summary(false)

SnapshotHelper Setup

1. Add SnapshotHelper.swift to your UI Test target
2. Import in your test file
3. Call setupSnapshot(app) in setUp

UI Test for Screenshots

Create YourAppUITests/ScreenshotTests.swift:

import XCTest

class ScreenshotTests: XCTestCase {

    var app: XCUIApplication!

    override func setUpWithError() throws {
        continueAfterFailure = false
        app = XCUIApplication()
        setupSnapshot(app)
        app.launch()
    }

    override func tearDownWithError() throws {
        app = nil
    }

    func testTakeScreenshots() throws {
        // Wait for app to load
        sleep(2)

        // 1. Home Screen
        snapshot("01_HomeScreen")

        // 2. Navigate to feature
        app.buttons["FeatureButton"].tap()
        sleep(1)
        snapshot("02_FeatureScreen")

        // 3. Navigate to another screen
        app.tabBars.buttons["Settings"].tap()
        sleep(1)
        snapshot("03_SettingsScreen")

        // 4. Show detail view
        app.cells["ProfileCell"].tap()
        sleep(1)
        snapshot("04_ProfileScreen")

        // 5. Dark mode (if applicable)
        // Toggle dark mode and capture
        snapshot("05_DarkModeScreen")
    }
}

Running Snapshot

cd ios

# Run all screenshots
fastlane snapshot

# Specific device only
fastlane snapshot --devices "iPhone 15 Pro Max"

# Specific language only
fastlane snapshot --languages "en-GB"

# Skip building (if already built)
fastlane snapshot --skip_build

Android Screenshot Automation (Screengrab)

Initialise Screengrab

cd android
fastlane screengrab init

Creates:

• fastlane/Screengrabfile - Configuration

Screengrabfile Configuration

# fastlane/Screengrabfile

# Package name
app_package_name("com.yourcompany.yourapp")

# Test instrumentation runner
use_tests_in_classes(["com.yourcompany.yourapp.ScreenshotTests"])

# APK paths
app_apk_path("app/build/outputs/apk/debug/app-debug.apk")
tests_apk_path("app/build/outputs/apk/androidTest/debug/app-debug-androidTest.apk")

# Locales for screenshots
locales([
  "en-US",
  "en-GB",
  "de-DE",
  "fr-FR",
  "ja-JP",
  "zh-CN"
])

# Output directory
output_directory("./fastlane/screenshots")

# Clear previous screenshots
clear_previous_screenshots(true)

# Exit on test failure
exit_on_test_failure(false)

# ADB path (optional)
# adb_path("/usr/local/bin/adb")

# Ending locale
ending_locale("en-US")

# Specific device serial (optional)
# specific_device("emulator-5554")

# Skip open summary
skip_open_summary(false)

Add Screengrab Dependency

In app/build.gradle:

dependencies {
    // ...
    androidTestImplementation 'tools.fastlane:screengrab:2.1.1'
}

Instrumented Test for Screenshots

Create app/src/androidTest/java/com/yourcompany/yourapp/ScreenshotTests.kt:

package com.yourcompany.yourapp

import androidx.test.core.app.ActivityScenario
import androidx.test.espresso.Espresso.onView
import androidx.test.espresso.action.ViewActions.click
import androidx.test.espresso.matcher.ViewMatchers.withId
import androidx.test.espresso.matcher.ViewMatchers.withText
import androidx.test.ext.junit.runners.AndroidJUnit4
import org.junit.Before
import org.junit.ClassRule
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith
import tools.fastlane.screengrab.Screengrab
import tools.fastlane.screengrab.UiAutomatorScreenshotStrategy
import tools.fastlane.screengrab.locale.LocaleTestRule

@RunWith(AndroidJUnit4::class)
class ScreenshotTests {

    companion object {
        @get:ClassRule
        @JvmStatic
        val localeTestRule = LocaleTestRule()
    }

    @Before
    fun setUp() {
        Screengrab.setDefaultScreenshotStrategy(UiAutomatorScreenshotStrategy())
    }

    @Test
    fun takeScreenshots() {
        ActivityScenario.launch(MainActivity::class.java)

        // Wait for app to load
        Thread.sleep(2000)

        // 1. Home Screen
        Screengrab.screenshot("01_HomeScreen")

        // 2. Navigate to feature
        onView(withId(R.id.feature_button)).perform(click())
        Thread.sleep(1000)
        Screengrab.screenshot("02_FeatureScreen")

        // 3. Navigate to settings
        onView(withId(R.id.settings_tab)).perform(click())
        Thread.sleep(1000)
        Screengrab.screenshot("03_SettingsScreen")

        // 4. Show profile
        onView(withText("Profile")).perform(click())
        Thread.sleep(1000)
        Screengrab.screenshot("04_ProfileScreen")
    }
}

Running Screengrab

cd android

# Build APKs first
./gradlew assembleDebug assembleAndroidTest

# Run screenshots
fastlane screengrab

# Specific locale
fastlane screengrab --locales "en-GB"

Framing Screenshots (Frameit)

Add device frames and marketing text to screenshots.

Basic Usage

# In screenshots directory
fastlane frameit

Configuration (frameit.json)

Create fastlane/screenshots/frameit.json:

{
  "default": {
    "title": {
      "font": "./fonts/Helvetica-Bold.ttf",
      "font_size": 128,
      "color": "#000000"
    },
    "background": "#FFFFFF",
    "padding": 50,
    "show_complete_frame": true,
    "stack_title": false
  },
  "data": [
    {
      "filter": "01_HomeScreen",
      "title": {
        "text": "Manage your tasks effortlessly"
      }
    },
    {
      "filter": "02_FeatureScreen",
      "title": {
        "text": "Powerful features at your fingertips"
      }
    },
    {
      "filter": "03_SettingsScreen",
      "title": {
        "text": "Customise to your needs"
      }
    },
    {
      "filter": "04_ProfileScreen",
      "title": {
        "text": "Your profile, your way"
      }
    }
  ]
}

Frameit Options

Option	Description
silver	Use silver device frame
rose_gold	Use rose gold frame
force_device_type	Force specific device
use_platform	Use platform-specific frames

# Silver frames
fastlane frameit silver

# Force iPhone 14 Pro frame
fastlane frameit --force_device_type "iPhone 14 Pro"

Fastfile Lanes

Define reusable workflows in Fastfile:

iOS Fastfile

# ios/fastlane/Fastfile

default_platform(:ios)

platform :ios do
  desc "Capture screenshots"
  lane :screenshots do
    snapshot
    frameit(white: true)
  end

  desc "Upload screenshots to App Store Connect"
  lane :upload_screenshots do
    deliver(
      skip_binary_upload: true,
      skip_metadata: true,
      screenshots_path: "./fastlane/screenshots"
    )
  end

  desc "Full screenshot workflow"
  lane :refresh_screenshots do
    screenshots
    upload_screenshots
  end
end

Android Fastfile

# android/fastlane/Fastfile

default_platform(:android)

platform :android do
  desc "Build debug APKs"
  lane :build_for_screenshots do
    gradle(
      task: "assemble",
      build_type: "Debug"
    )
    gradle(
      task: "assemble",
      build_type: "AndroidTest"
    )
  end

  desc "Capture screenshots"
  lane :screenshots do
    build_for_screenshots
    screengrab
  end

  desc "Upload screenshots to Play Console"
  lane :upload_screenshots do
    supply(
      skip_upload_apk: true,
      skip_upload_aab: true,
      skip_upload_metadata: true,
      skip_upload_changelogs: true,
      images_path: "./fastlane/screenshots"
    )
  end
end

Running Lanes

# iOS
cd ios
fastlane screenshots
fastlane upload_screenshots

# Android
cd android
fastlane screenshots
fastlane upload_screenshots

Required Screenshot Sizes

iOS (App Store Connect)

Display Size	Resolution	Device
6.7"	1290 x 2796	iPhone 15 Pro Max
6.5"	1284 x 2778	iPhone 14 Plus
5.5"	1242 x 2208	iPhone 8 Plus
12.9" iPad	2048 x 2732	iPad Pro

Note: App Store Connect can auto-scale from 6.7" to smaller sizes.

Android (Play Console)

Type	Minimum	Recommended
Phone	320px min side	1080 x 1920
7" Tablet	1024 x 500	1200 x 1920
10" Tablet	1024 x 500	1600 x 2560

Localisation

Setting Up Localised Screenshots

1. Configure languages in Snapfile/Screengrabfile
2. Use localised strings in your app
3. Capture screenshots for each locale

iOS Localisation in Tests

func testTakeLocalizedScreenshots() throws {
    // The locale is set automatically by snapshot
    // Just ensure your app uses NSLocalizedString

    snapshot("01_HomeScreen")
    // Screenshots saved to: en-GB/01_HomeScreen.png, de-DE/01_HomeScreen.png, etc.
}

Android Localisation in Tests

@Test
fun takeLocalizedScreenshots() {
    // LocaleTestRule handles locale switching
    // Just ensure your app uses string resources

    Screengrab.screenshot("01_HomeScreen")
    // Screenshots saved to: en-US/01_HomeScreen.png, de-DE/01_HomeScreen.png, etc.
}

Troubleshooting

Common iOS Issues

Simulator not found:

# List available simulators
xcrun simctl list devices

# Check exact device name in Snapfile
devices(["iPhone 15 Pro Max"])  # Must match exactly

UI test target issues:

• Ensure SnapshotHelper.swift is in UI Test target
• Check scheme includes UI Test target
• Verify setupSnapshot(app) is called

Status bar not overridden:

# In Snapfile
override_status_bar(true)

Common Android Issues

APK not found:

# Build APKs first
./gradlew assembleDebug assembleAndroidTest

# Check paths in Screengrabfile match actual output

Emulator connection issues:

# Check emulator is running
adb devices

# Start emulator if needed
emulator -avd Pixel_6_API_34

Permission issues:

// Add to test class
@get:Rule
val grantPermissionRule: GrantPermissionRule =
    GrantPermissionRule.grant(Manifest.permission.WRITE_EXTERNAL_STORAGE)

General Issues

Screenshots too slow:

• Use concurrent_simulators(true) (iOS)
• Run fewer devices at once
• Use skip_build if already built

Memory issues:

# Limit concurrent simulators
# In Snapfile
number_of_retries(3)
concurrent_simulators(false)

Best Practices

Screenshot Quality

1. Use realistic data - Not Lorem ipsum
2. Clean status bar - Use override_status_bar
3. Consistent state - Reset app between captures
4. Wait for animations - Add appropriate sleeps/waits
5. Test edge cases - Empty states, full lists, etc.

Organisation

1. Name screenshots descriptively - 01_Home, 02_Feature
2. Use consistent numbering - Ensures correct order
3. Group by feature - Logical organisation
4. Document test scenarios - What each screenshot shows

Performance

1. Build once, capture many - Use skip_build
2. Parallel capture - concurrent_simulators(true)
3. Target specific devices - When debugging
4. CI integration - Automate in pipeline

Quick Reference

# iOS
cd ios
fastlane snapshot init          # First time setup
fastlane snapshot               # Capture screenshots
fastlane frameit               # Add device frames
fastlane deliver screenshots   # Upload to ASC

# Android
cd android
fastlane screengrab init       # First time setup
./gradlew assembleDebug assembleAndroidTest
fastlane screengrab            # Capture screenshots
fastlane supply images         # Upload to Play Console

# Specific options
fastlane snapshot --devices "iPhone 15 Pro Max"
fastlane snapshot --languages "en-GB,de-DE"
fastlane snapshot --skip_build
fastlane screengrab --locales "en-US"

Integration with EAS/Expo

For Expo projects:

1. Run npx expo prebuild to generate native projects
2. Configure Fastlane in ios/ and android/ directories
3. Run screenshot automation as normal
4. Native projects are regenerated on prebuild, so:
   • Keep Fastfile in project root, copy on prebuild
   • Or add to .gitignore and regenerate as needed

# In package.json scripts
{
  "screenshots:ios": "cd ios && fastlane snapshot",
  "screenshots:android": "cd android && fastlane screengrab"
}