i am using windows machine & android phones for private instance
now i want to use iphone device.
i got old iphone 4 with ios 7.1.2
will i able to use as mobile agent or i have to buy latest iphone ?
it will connect to windows macine or mac needed ?
It depends if you want to be able to capture video. If you want video capture (which is critical for the visual metrics) then you need a dedicated Mac for every iPhone and the iPhone needs to be connected by lightning cable (iPhone 5 or newer pretty much).
You also need to be able to jailbreak the device so watch out for what version of iOS is installed/updated (the latest is usually not able to be jailbroken).
The iOS devices are an order of magnitude more time consuming to run because they are also not as stable as the android devices and require manual rebooting from time to time.