Project Configurations for iOS

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This document presents in detail the set of configurations used in the iOS projects developed at Nimble. It includes:

  • Terminologies and topics related to project configurations.
  • Basic targets, schemes, build settings options, etc., for building a project.


A target specifies a product to build, such as an iOS, watchOS, or macOS app.

When creating a project from a template, a default target will be added automatically for the main application.

There are three default targets in a project:

  • {ProjectName}
  • {ProjectName}Tests
  • {ProjectName}UITests


A scheme is a collection of settings that specifies the targets to build for a project, the build configuration to use, and the executable environment to use when the application is launched.

The two main schemes in a project:

  • {ProjectName}
  • {ProjectName} Staging

Build Configurations in Schemes

It is possible to build a scheme with different Build Configurations. Initially, there are two basic configurations for a project generated automatically by Xcode, which are:

  • Debug
  • Release

However, these basic configurations are not enough for the development process. Since the team always wants to ensure the application is working in a designated manner, additional levels of testing are required before the application is ready to be used.

The recommended set of configurations to have is:

  • Debug Staging
  • Release Staging
  • Debug Production
  • Release Production

Active Compilation Conditions

Having distinct flags for each configuration is the preferred solution.

Xcode provides a build setting named Active Compilation Conditions, which supports passing conditional compilation flags to the Swift compiler.

In the iOS template project, there are three custom conditional compilation flags: DEBUGSTAGINGPRODUCTION. The following table will describe how the developers differentiate a configuration from the others.

Debug Staging ✔︎ ✔︎  
Release Staging   ✔︎  
Debug Production ✔︎   ✔︎
Release Production     ✔︎

The considerable advantage when using custom flags is customizable specific features based on a particular environment.

Example: Specify a value based on the environment:

enum Environment {

    static func based<T>(staging: T, production: T) -> T {
        #if PRODUCTION
        return production
        return staging

During the development process, all functionalities and frameworks are available in the application. However, there can be situations when the developer turns on some features for a particular environment without creating separate modules for the application. In these cases, taking advantage of Active Compilation Conditions by declaring a condition to include or exclude code is the recommended solution.

    // Code the app includes in DEBUG environments
    // Code the app includes when it is not build with DEBUG environments

Xcode Configuration File

A Configuration Settings File (*.xcconfig), also known as a build configuration file, is a plain text file that defines and overrides the build settings for a particular build configuration of a project or target. This type of file can be edited outside of Xcode and integrates well with source control systems.

Because of different settings for each environment (such as bundle identifiers, endpoints, etc.), the developers also define them in different *.xcconfig files.

Settings Bundle

To support multiple levels of testing, the Settings Bundle is usually integrated along with the dev configurations. In addition, the Settings Bundle facilitates the testing process. It creates a shortcut to change environment values without using any third-party API or server.

Settings Bundle works well when developing:

  • Feature toggle.
  • A/B Testing.
  • Change API endpoints for testing the application with multiple servers.
  • Define a list of prefilled credentials and a toggle for prefilling.

The Settings Bundle is only enabled on Dev environments. It is optional for Beta environments.

Debug Symbol File

The debug Symbol file (dSYM file) is used to de-obfuscate stack traces from crashes on the production app. The dSYM files store the debug symbols for the application. Then services (like Crashlytics) use the dSYM files to replace the symbols in the crash reports with the originating locations in the source code. Hence, the crash reports will be more readable and understandable.

Go to Build SettingDebug Information Format. The debug symbols with a dSYM file (DWARF with dSYM file) are enabled for the release build by default.

A benefit of using the dSYM is reducing the binary size when building an application. Read more about it in the document Diagnosing Issues Using Crash Reports and Device Logs.

Only include the dSYM file for release builds.

Build Configurations Included dSYM file
Debug Staging  
Release Staging ✔︎
Debug Production  
Release Production ✔︎

Enable Bitcode

Bitcode is a technology that enables recompiling applications to reduce their size. It is used to optimize the production build before uploading to the App Store.

Build configurations Enable Bitcode
Debug Staging  
Release Staging  
Debug Production  
Release Production ✔︎