However, this process is heavily restricted by Apple. Here is how it works and why it is difficult.

Developers often need to test apps on older versions of iOS. This is done through the included with Xcode on macOS.

Apple uses a security mechanism called "SHSH Blobs." When you restore an iPhone via iTunes (or Finder), the device "phones home" to Apple servers to ask permission to install that specific version of iOS.

These are modified versions of Android (like the Puck iOS mod ) designed for specific Android devices to give them an iOS 9 interface. 2. Where to Download iOS 9 Firmware (for Apple Devices)

Some people confuse “iOS ROM” with “macOS VM.” You can run macOS in a virtual machine on Windows using Unlocker and VMware, but iOS is a completely different operating system, compiled for ARM. VirtualBox and VMware are x86 hypervisors. Unless you use QEMU (with its performance problems), it won’t work.