Recently we migrated our crash report SDK from Fabric Crashlytics to Firebase Crashlytics.

Here’s the note:
I assume that the app has been migrated to Firebase, and you can see crashes on dashboard.

Follow the steps in the document
https://firebase.google.com/docs/crashlytics/get-started-new-sdk?platform=ios

Install new SDK

Replace

pod 'Fabric'
pod 'Crashlytics'

with

pod 'Firebase/Crashlytics'

Configure for different env

Download all GoogleService-Info.plist files form your different projects and drag and drop into the Xcode project.

Remember rename them according to env or something you can recognize.
Ex: GoogleService-Info-Staging.plist, GoogleService-Info-Production.plist

Configure multiple environment in AppDelegate

#ifdef STAGING
    filePath = [[NSBundle mainBundle] pathForResource:@"GoogleService-Info-Staging" ofType:@"plist"];
#elif defined PROD
    filePath = [[NSBundle mainBundle] pathForResource:@"GoogleService-Info-Production" ofType:@"plist"];
#endif
    FIROptions *options = [[FIROptions alloc] initWithContentsOfFile:filePath];
    [FIRApp configureWithOptions:options];

Update run script

AppStoreConfiguration="AppStore"
DevReleaseConfiguration="Dev Release"
StagingReleaseConfiguration="Staging Release"
ProdReleaseConfiguration="Prod Release"

if [ "$AppStoreConfiguration" = "${CONFIGURATION}" ]; then
echo "Running Crashlytics (AppStore)"
"${PODS_ROOT}/FirebaseCrashlytics/run" -gsp "${PROJECT_DIR}/wapos-iPad/GoogleService-Info-Production.plist"
echo "Uploading dSYM"
find "${DWARF_DSYM_FOLDER_PATH}" -name "*.dSYM" | xargs -I \{\} "${PODS_ROOT}/FirebaseCrashlytics/upload-symbols" -gsp "${PROJECT_DIR}/wapos-iPad/GoogleService-Info-Production.plist" -p ios \{\}
elif [ "$ProdReleaseConfiguration" = "${CONFIGURATION}" ]; then
echo "Running Crashlytics (Release)"
"${PODS_ROOT}/FirebaseCrashlytics/run" -gsp "${PROJECT_DIR}/wapos-iPad/GoogleService-Info-Production.plist"
echo "Uploading dSYM"
find "${DWARF_DSYM_FOLDER_PATH}" -name "*.dSYM" | xargs -I \{\} "${PODS_ROOT}/FirebaseCrashlytics/upload-symbols" -gsp "${PROJECT_DIR}/wapos-iPad/GoogleService-Info-Production.plist" -p ios \{\}
elif [ "$StagingReleaseConfiguration" = "${CONFIGURATION}" ]; then
echo "Running Crashlytics (Staging)"
"${PODS_ROOT}/FirebaseCrashlytics/run" -gsp "${PROJECT_DIR}/wapos-iPad/GoogleService-Info-Staging.plist"
echo "Uploading dSYM"
find "${DWARF_DSYM_FOLDER_PATH}" -name "*.dSYM" | xargs -I \{\} "${PODS_ROOT}/FirebaseCrashlytics/upload-symbols" -gsp "${PROJECT_DIR}/wapos-iPad/GoogleService-Info-Staging.plist" -p ios \{\}
elif [ "$DevReleaseConfiguration" = "${CONFIGURATION}" ]; then
echo "Running Crashlytics (Dev)"
fi

Migrate some methods.

https://firebase.google.com/docs/crashlytics/upgrade-sdk?platform=ios#the_library_is_now_called_firebasecrashlytics

Last step, remove Fabric API Key setting from info.plist.

OK, that’s it.