Wi-Fi Direct and iOS Support
It took me a while to find out what is going on, but here is the summary. I hope this save people a lot of time.
Apple are not playing nice with Wi-Fi Direct, not in the same way that Android is. The Multipeer Connectivity Framework that Apple provides combines both BLE and WiFi Direct together and will only work with Apple devices and not any device that is using Wi-Fi Direct.
https://developer.apple.com/library/ios/documentation/MultipeerConnectivity/Reference/MultipeerConnectivityFramework/index.html
It states the following in this documentation - "The Multipeer Connectivity framework provides support for discovering services provided by nearby iOS devices using infrastructure Wi-Fi networks, peer-to-peer Wi-Fi, and Bluetooth personal area networks and subsequently communicating with those services by sending message-based data, streaming data, and resources (such as files)."
Additionally, Wi-Fi direct in this mode between i-Devices will need iPhone 5 and above.
There are apps that use a form of Wi-Fi Direct on the App Store, but these are using their own libraries.
According to this thread:
The peer-to-peer Wi-Fi implemented by iOS (and recent versions of OS X) is not compatible with Wi-Fi Direct. Note Just as an aside, you can access peer-to-peer Wi-Fi without using Multipeer Connectivity. The underlying technology is Bonjour + TCP/IP, and you can access that directly from your app. The WiTap sample code shows how.
The official list of current iOS Wi-Fi Management APIs
There is no Wi-Fi Direct type of connection available. The primary issue being that Apple does not allow programmatic setting of the Wi-Fi network SSID and password. However, this improves substantially in iOS 11 where you can at least prompt the user to switch to another WiFi network.
QA1942 - iOS Wi-Fi Management APIs
Entitlement option
This technology is useful if you want to provide a list of Wi-Fi networks that a user might want to connect to in a manager type app. It requires that you apply for this entitlement with Apple and the email address is in the documentation.
- NEHotspotHelper
MFi Program options
These technologies allow the accessory connect to the same network as the iPhone and are not for setting up a peer-to-peer connection.
- Wireless Accessory Configuration (WAC)
- HomeKit
Peer-to-peer between Apple devices
These APIs come close to what you want, but they're Apple-to-Apple only.
- NSNetService
- Multipeer Connectivity
WiTap Example Code
iOS 11 NEHotspotConfiguration
Brought up at WWDC 2017 Advances in Networking, Part 1 is NEHotspotConfiguration which allows the app to specify and prompt to connect to a specific network.