Apple is working on integrating the Gemini chatbot into Apple Intelligence. Information about this appeared in the beta version of iOS 18.4. This is reported by 9to5Mac.
Apple Intelligence now allows users to send queries to ChatGPT to get more contextual answers than Siri can provide. Apple Software Chief Craig Federighi said at WWDC 24 that the company is looking to integrate other AI models.
This doesn't necessarily confirm that Gemini will be integrated into iOS 18.4, especially given all the other Apple Intelligence delays.
Incidentally, Google recently released several new Gemini 2.0 models, including one optimized for complex reasoning. It's likely that these updated models could be coming to the iPhone in the near future.