Dynamic bundle identifiers in Xcode: Using xcconfig for different configurations

• Published: 17 July 2025

Generally in Xcode you have two configurations: Debug and Release. It's often a good idea to have a different bundle identifier for each configuration so that your debug builds don't replace the release builds on your device.

Normal setup

For a single target I usually start with three xcconfig files: Base.xcconfig, Debug.xcconfig and Release.xcconfig. Base.xcconfig is for build settings shared by both configurations. Versions for each app/extension need to match so that's a good thing to place in your Base.xcconfig:

// Base.xcconfig
MARKETING_VERSION = 1.0
CURRENT_PROJECT_VERSION = 1

Debug.xcconfig and Release.xcconfig then look like this:

// Debug.xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = "me.annema.app-name.ios.dev"

// Release.xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = "me.annema.app-name.ios"

See Map build settings to a build configuration for instructions on how to configure your project to use the xcconfig files.

Safari extension

I'm working on a Safari extension which comes with 4 different targets: iOS app, iOS extension, macOS app and macOS extension. With the above approach that would mean 8 separate xcconfig files that are almost identical. The odds of a typo or copy-paste error are high. I want a single xcconfig file per target that has the dev suffix for Debug builds and no suffix for Release builds.

Conditional values

The first obvious thing I tried was to define conditional Debug and Release values:

// Base.xcconfig
PRODUCT_BUNDLE_IDENTIFIER_PREFIX = me.annema.safari-extension
PRODUCT_BUNDLE_IDENTIFIER_SUFFIX[config=Debug] = .dev

// iOS (App).xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = $(PRODUCT_BUNDLE_IDENTIFIER_PREFIX)$(PRODUCT_BUNDLE_IDENTIFIER_SUFFIX)

I expected this to resolve to:

• Debug: me.annema.annema.safari-extension.dev
• Release: me.annema.safari-extension

But each configuration resolves to me.annema.safari-extension instead.

The trick

It's then I realized references can be nested:

// Base.xcconfig
BUNDLE_ID_SUFFIX_Debug = dev
BUNDLE_ID_SUFFIX_Release =

PRODUCT_BUNDLE_IDENTIFIER_SUFFIX = $(BUNDLE_ID_SUFFIX_$(CONFIGURATION))

Xcode sees the $(CONFIGURATION) and replaces it with Debug or Release. The outer $() then becomes $(BUNDLE_ID_SUFFIX_Debug) or $(BUNDLE_ID_SUFFIX_Release) which Xcode replaces with one of the values we've defined on the first two lines: dev for BUNDLE_ID_SUFFIX_Debug and nothing for BUNDLE_ID_SUFFIX_Release.

The result

To get the final bundle identifier we need to combine the prefix with the suffix and make the value unique for each target. The final Base.xcconfig therefor defines both a prefix and a suffix:

// Base.xcconfig
BUNDLE_ID_SUFFIX_Debug = .dev
BUNDLE_ID_SUFFIX_Release =

PRODUCT_BUNDLE_IDENTIFIER_PREFIX = me.annema.safari-extension
PRODUCT_BUNDLE_IDENTIFIER_SUFFIX = $(BUNDLE_ID_SUFFIX_$(CONFIGURATION))

The app specific xcconfigs combine the prefix and suffix:

// iOS (App).xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = $(PRODUCT_BUNDLE_IDENTIFIER_PREFIX).ios$(PRODUCT_BUNDLE_IDENTIFIER_SUFFIX)

// iOS (Extension).xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = $(PRODUCT_BUNDLE_IDENTIFIER_PREFIX).ios$(PRODUCT_BUNDLE_IDENTIFIER_SUFFIX).web-extension

// macOS (App).xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = $(PRODUCT_BUNDLE_IDENTIFIER_PREFIX).macos$(PRODUCT_BUNDLE_IDENTIFIER_SUFFIX)

// macOS (Extension).xcconfig
#include "Base.xcconfig"

PRODUCT_BUNDLE_IDENTIFIER = $(PRODUCT_BUNDLE_IDENTIFIER_PREFIX).macos$(PRODUCT_BUNDLE_IDENTIFIER_SUFFIX).web-extension

The final bundle identifiers resolve to the following. Note that web-extension is a suffix, this is required because an extension's bundle identifier needs to be prefixed by the bundle identifier of the containing app.