Strange iOS behavior when using NSNetService and NSNetServiceBrowser?

Question

Objective-C

In the application, I create a network service using NSNetService and after that I start looking for the same services using NSNetServiceBrowser.
I run the application on the iPhone and then on the iPad. Wi-Fi is enabled on both devices, both are connected to the same network. Bluetooth is also enabled on the devices.
When, for example, the iPhone finds the iPad, they begin to interact by sending each other some data via Sockets. When an interaction occurs, the Bluetooth icons on both devices become active. If you close/minimize the application, the Bluetooth icon becomes inactive.
What caused this behavior of the device? Can the connection be made via Bluetooth?
PS There are no Bluetooth devices nearby that could connect iPhone and iPad.