r3to / White-Labelling-Swift-App

README

This is an example for the setup of a white labeling app which uses build configurations and schemes instead of targets to differentiate between different implementation.

tl;dr

We separate customer specific assets and configurations in different directories and use build configurations to include only those files, that are needed per implemenation.

Reading Resources

• Conditional Compilation, Part 2: Including and Excluding Source Files
• Xcode Build Settings
• White-Labeling in Xcode

Project Structure

For each customer, we define two build configurations (one for debugging and one for releasing). Going further, we can move that to a custom .xccconfig file.

We organize different files in distinct subdirectories and use EXCLUDED_SOURCE_FILE_NAMES together with INCLUDED_SOURCE_FILE_NAMES to exclude resources that belong to a different customer.

Example

In BaseWhiteLabelConfiguration.xcconfig we define the paths for all customer implementations

CLIENT_PATHS = */ClientA/* */ClientB*/

EXCLUDED_SOURCE_FILE_NAMES = $CLIENT_PATHS
INCLUDED_SOURCE_FILE_NAMES = */$(CLIENT)/*

In the build configuration for each customer, we set the $(CLIENT) value to the correct name.

Custom Swift Implementations per Customer

Excluding Swift files doesn't work that well. Xcode will return a Invalid redeclaration of 'X' error when defining custom implementations in the Customer's subdirectory. As a workaround, the value of $(CLIENT) is added to SWIFT_ACTIVE_COMPILATION_CONDITIONS. We can then wrap the whole implmentation in a conditional statement.

#if ClientB
import UIKit

struct Client: Whitelabelable {
    var name: String { return "Client A" }
    var tintColor: UIColor { return .blue }
}
#endif

Adding A New Customer

1. Creating subdirectory
2. Adding directory to $(CLIENT_PATHS) in BaseWhiteLabelConfiguration.xcconfig
3. Creating new build configurations (Debug and Release)
   • Duplicate existing configurations
   • Set $(CLIENT) to the correct name
   • -> TODO: have a base implementation, that can be copy-pasted
4. Create a build scheme for the new customer
5. Adjust configuration to match the customers specification

Considerations

• Multiple targets can become messy
• Separate icons, certificates and configuration per App
• Simple is better than complicated
• Possible alternative: use Swift packages for different components and configurations