How do you configure an iOS app to support multiple environments (Dev, SIT, UAT, Prod) so all can be installed simultaneously on the same device?

Use separate Xcode Schemes, Build Configurations, Bundle Identifiers, and Firebase plists — one set per environment.

Environment	Bundle ID Suffix	Firebase Plist	App Display Name
Dev	.dev	GoogleService-Info-Dev.plist	YourApp Dev
SIT	.sit	GoogleService-Info-SIT.plist	YourApp SIT
UAT	.uat	GoogleService-Info-UAT.plist	YourApp UAT
Prod	(none)	GoogleService-Info.plist	YourApp

Step-by-step:

1. Schemes — Product → Scheme → Manage Schemes → + → name it Dev, SIT, UAT (Prod reuses the default).
2. Build Configurations — Project (root) → Info → Configurations → + (Duplicate) → name to match environment.
3. Link scheme to config — Edit Scheme → each action (Run/Test/Archive/etc.) → set Build Configuration to the matching one.
4. Firebase plists — Download from each Firebase console, rename (GoogleService-Info-Dev.plist, etc.), drag all into Xcode with Target Membership checked. Do not conditionally exclude them from the bundle — all four must be present at runtime.
5. Active Compilation Conditions — Target → Build Settings → Active Compilation Conditions → set Dev, SIT, UAT per config; leave Prod empty.
6. Bundle Identifiers — Signing & Capabilities → switch configuration → set unique bundle ID per config.
7. App Display Name — Add a User-Defined Build Setting APP_DISPLAY_NAME with a value per config, then set CFBundleDisplayName = $(APP_DISPLAY_NAME) in Info.plist.