Well I'm working on this app to send data between android and iOS and I got it to work between iOS devices with Apple's Multipeer Connectivity framework, but I am currently wondering how do you achieve it between both platforms? even if you are willing to write it from scratch.
How come Firechat is able to do it? As I remember, you can exchange data between both platforms with their app.
Edit: https://www.opengarden.com/meshkit.html It seems the MeshKit SDK used in Firechat is now available (for large organisations).
I am very interested in this subject as well and I came across these links
AllJoyn
AllJoyn® is a collaborative open-source software framework that makes it easy for developers to write applications that can discover nearby devices, and communicate with each other directly regardless of brands, categories, transports, and OSes without the need of the cloud Source: https://allseenalliance.org/developers/learn
OpenPeer SDK
Open Peer is an open P2P signalling protocol Source: http://openpeer.org/open-peer-sdk-for-ios/
Microsoft's Project Rome
"Project Rome" is a project code name for Microsoft's cross-device experiences platform using the Microsoft Graph. Source: https://docs.microsoft.com/en-us/windows/uwp/launch-resume/communicate-with-a-remote-app-service
Mutipeer connectivity cannot connect iOS and Android devices. Firechat is using its own implementation.
More information here:
A couple of weeks after its iOS launch, FireChat made its debut on Android. Since Android doesn’t support Apple’s Multipeer Connectivity Framework, developer Open Garden had to build its own mesh networking technology to enable off-the-grid messaging across Android devices. However, FireChat messaging hasn’t been possible between iOS and Android. That is, until now. Open Garden has just updated FireChat to allow for off-the-grid messaging even between iOS and Android devices. While it declines to reveal the exact details of how it managed to make Apple’s multi-peer framework and its Android mesh network connect with each other, Open Garden has told TechCrunch that its cross-platform capability uses peer-to-peer Wi-Fi and Bluetooth personal area networking.
Something like text chat can be done over BLE, which is open on both platforms. Sending images would be slow, though, since it doesn't have the throughput of Bluetooth Classic.
You'll want to look into iotivity. https://iotivity.org/ This is the new upcoming inter-device library that the Open Connectivity Foundation is focusing on.
AllJoyn is only being maintained now, and has some significant underlying threading problems that will never be fixed, making call-response type workflows between devices prone to crashing and deadlocking the application code. I don't recommend using it.
来源：https://stackoverflow.com/questions/28906948/peer-to-peer-android-and-ios-with-wifi-direct-multipeer-connectivity