...Structured using GCD, this framework performs well regardless of whether it's being run on an old iPhone, or on a 12-core Mac Pro. (And it won't block the main thread at all). There have been a number of changes to the public API of XMPPFramework in an attempt to improve the ergnomics and safety when used with Swift. Most Objective-C projects should require no changes, with a few minor exceptions. Many (simple) changes will be required for pure Swift projects, mostly due to the new nullability annotations. The process is still not complete so please submit issues and help if possible to minimize future breaking changes.