just jailbreak your iOS 8.4 device with Taig v 2.4.3 to download Cydia
https://www.facebook.com/pages/Jailbreak-iOS/1433510436952744
https://twitter.com/olivia77aurora
https://plus.google.com/u/0/114258076444527929372/posts
http://evasion7.com/Jailbreak-iOS-8.4
