Remember, too, that another recent iOS 7 device can also run as a BTLE "client" and pair: that's how testing iBeacons works.
You can pick up an iPod Touch and write an app for it that uses the Touch's sensors to do what your custom hardware could do, to get further than you might if you had to start from hardware alone. Additionally, integrating new sensors into the Touch could be done more simply via the headphone jack using an Arduino: http://www.creativedistraction.com/demos/sensor-data-to-ipho... or using Project HiJack: http://web.eecs.umich.edu/~prabal/projects/hijack/
Once you've got a version using an iPod Touch and a custom sensor working, you'd have a complete test case and prototype to develop original hardware against.
You can pick up an iPod Touch and write an app for it that uses the Touch's sensors to do what your custom hardware could do, to get further than you might if you had to start from hardware alone. Additionally, integrating new sensors into the Touch could be done more simply via the headphone jack using an Arduino: http://www.creativedistraction.com/demos/sensor-data-to-ipho... or using Project HiJack: http://web.eecs.umich.edu/~prabal/projects/hijack/
Once you've got a version using an iPod Touch and a custom sensor working, you'd have a complete test case and prototype to develop original hardware against.