According to the sources, the specifics of Google's plans for Assistant on iOS remain unclear as of now, but the app is predicted to combine the chatbot-like features of Google Allo with voice controls found on Android smartphones.
More solid details about the Google Assistant iOS app point towards a United States-only launch, and an official announcement coming "in fairly short order."
According to a trusted source, Google plans to announce that the Google Assistant will be launching on iOS soon as a standalone app. The announcement could come as soon as Google's I/O conference this week, but it's unclear exactly what Google's plans are at this time. The app would likely feature a blend of the "chat" style functionality in the Google Allo version of Assistant and the voice-controlled version found on Android, but again, details are scant.Microsoft has launched its own smart assistant Cortana on iOS in the past, allowing more users to gain access to the assistant than if it remained exclusive to the company's own devices. If Google Assistant does come to iPhone and iPad, it'll mark a continued expansion of the AI, after Google first launched Assistant on Pixel devices, Google Home, the Google Allo app, and then expanded to Android smartphones.
We do know that the Assistant for iOS will only be available in the US at launch, and that Google plans to make the announcement in fairly short order. I/O would be a pretty ideal venue for such a launch, as Assistant's SDK was just made available to developers late last month. Bringing the Assistant to the world's second-largest mobile OS would likely encourage more developers to integrate with the app's functionality.