Technical documentation and specification
License

Actual End User License Agreement applied to SDKs.

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Android 2.2+ to 5.x
Development tools: Java within AndroidStudio and Eclipse

JavaDocs documentation with Java reference.

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iOS 6.x to 8.x
Development tools: Objective-C within XCode   

HTML documentation with Objective-C reference.

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Windows/WindowsPhone 8.1 and Windows 10 UWP
Development tools: C# within VisualStudio 2013+

HTML documentation with C# reference.

Windows WindowsPhone