mixpanel/mixpanel-swift v2.6.4

v2.6.4 - race condition bug fixes

on GitHub

PR: #322

• Crash with Set.contains(_:)
  #321
• MixpanelInstance.checkDecide crash
  #312
• Crash in Persistence
  #310
• Bad Access in Global Lock
  #309

PR: #317 Thanks @RamblinWreck77 !

• Crash in Network.swift
  #314

PR: #305

• A/B Developer tweaks won't update
  #302