To add custom icons specific to iOS, they should be placed in the ________ folder.

Custom icons specific to iOS in a Flutter project should be placed in the 'ios' folder. This folder contains platform-specific configurations and assets for iOS. Placing custom icons in the 'ios' folder ensures that they are included correctly when building the iOS version of the app. Understanding how to structure and manage platform-specific assets is crucial for creating a consistent and polished user experience across different devices.