With the latest Apple iOS improvements, and support for IKEv2, it's now possible to establish a VPN connection between Apple iPhone/iPad devices and Juniper SRX devices.
Note: You must have Apple iOS 9.x installed and have access to an Apple MAC to prepare an Apple VPN profile.
Read Milan's attached PDF, which provides instructions based on his personal lab tests.
Note: The same VPN profile can be used on a Apple Mac, at least on MacBook Pro, with El Capitan OSX (what Milan tested).