Both directions of the switch have official one-cable tools that move photos, contacts, and most messages. The pain lives in three specifics: iMessage, app purchases, and your 2FA codes. Handle those and it's a calm afternoon.
Quinn Yoo
Update the old phone, connect to Wi-Fi and power, and run fresh backups: iCloud or Finder backup for iPhone, Google backup for Android, and WhatsApp's own chat backup (Settings -> Chats -> Chat backup) since chats transfer differently than the rest. Confirm you know your Apple ID/Google account passwords - half of switch-day misery is password resets.
Audit the irreplaceables: photos backed up and verified, the authenticator app's transfer/export located (this matters more than anything - see below), and any app with local-only data noted: voice memos, game saves without cloud sync, voicemail recordings, and downloaded music. Keep the old phone alive and un-wiped until everything is confirmed on the new one; it is your safety net for weeks, not hours.
iPhone -> Android: Google's 'Switch to Android'/Pixel setup transfers over a cable (or Wi-Fi) during the new phone's setup: photos, videos, contacts, calendar, SMS history, and free apps that exist on Android. Samsung's Smart Switch does the same for Galaxy phones and is genuinely good - cable transfer is faster and more complete than wireless for both.
Android -> iPhone: Apple's 'Move to iOS' app runs during iPhone setup and brings contacts, messages, photos, WhatsApp chats (it has a dedicated WhatsApp handover), and more. In both directions the cardinal rule is the same: do the transfer DURING initial setup - retrofitting data onto an already-set-up phone is messier, and Move to iOS in particular requires a reset to redo.
iMessage routes texts between Apple devices over the internet - and if you leave the ecosystem without telling it, texts from iPhone friends keep flowing to your dormant iMessage identity and never reach the Android. The fix takes two minutes: on the iPhone before wiping, Settings -> Messages -> iMessage OFF (and FaceTime off too); then, belt-and-braces, deregister the number at Apple's 'Deregister iMessage' web page (it sends a code, works even after the phone is wiped).
Going the other way (Android -> iPhone) has the milder equivalent: RCS chats on Android should be turned off in Google Messages before the move so group texts don't strand. Either direction, send yourself test texts from a friend on each platform on day one - it is the fastest way to confirm message routing is clean.
Paid apps don't cross stores: an app bought on the App Store must be re-bought on Google Play and vice versa - though most subscription services (Spotify, Netflix, YouTube Premium) just log back in, since the subscription lives with the account, not the store. In-app purchases and game progress depend on the developer: games tied to a cross-platform account (or Facebook login) carry; purely local saves don't. Check your two or three most-played games' transfer process before the switch, not after.
The other classic strandings: Apple Watch only pairs with iPhones (a Watch is effectively a vote against switching), authenticator apps need their explicit export/transfer flow run (Google Authenticator: Settings -> Transfer accounts; or migrate to a synced authenticator first), Safari/Chrome passwords export-import via each browser's settings or - better - live in a cross-platform password manager already, and music libraries: Apple Music works fine on Android, but locally synced MP3s and old iTunes purchases need re-downloading on a computer and re-uploading to YouTube Music or similar.
Day one: verify the big four - photos (count a recent album on both phones), contacts, messages (test texts both directions), and WhatsApp history. Re-enroll banking apps (most require re-verification on a new device - have your card and ID handy), re-pair Bluetooth devices and the car, and rebuild the 2FA apps from your export or backup codes.
Then give the muscle memory a fair trial: both platforms have remapped each other's best ideas, and the genuine friction - different gestures, notification styles, where settings live - fades in about a week. Keep the old phone in a drawer, un-wiped, for two to four weeks until nothing has surfaced missing; then sign out of accounts, run the factory reset, and trade it in while it still has value.
Not anymore - Move to iOS transfers WhatsApp history Android->iPhone, and WhatsApp's own transfer tools (and Smart Switch) handle iPhone->Android. The chats move device-to-device during setup; the old iCloud/Google chat backups don't cross platforms, so do the transfer rather than relying on backup restore.
Your number is still registered to iMessage, so iPhones are delivering to your ghost. Turn iMessage off on the old phone or use Apple's web deregistration page - delivery returns to normal SMS/RCS within a day at most.
Cable transfers and proper cloud sync move original files at full quality. The quality trap is sharing photos to yourself via messaging apps, which compress aggressively - use the transfer tool, Google Photos/iCloud sync, or a computer copy instead.
Keep it intact for a few weeks as the safety net, then: sign out of iCloud/Google (this releases activation locks - required for the next owner), factory reset, and remove the SIM/eSIM. Trade-in values drop steadily, so don't let it ride the drawer for a year.
