When exactly is the implementation of a function or component carried out during development?

The implementation of a function or component occurs after the design and planning phase, when requirements and architecture are defined. At this stage, the developer writes code that performs a specific task or provides the functionality of the component. This usually happens after the interface and interaction design are agreed upon, and before the testing phase. In iOS development, implementation may include writing Swift or Objective-C code, setting up the UI, and integrating with other modules.