When building When building for Venmo, we wanted to be able to let the user know that they needed to turn Bluetooth on in order to see people nearby & most of the available options either triggered a permissions dialog, or a dialog letting the user know to turn Bluetooth on at app open.. neither of which we want.

Eventually we found the CBCentralManagerOptionShowPowerAlertKey key, which can be passed to the initWithDelegate:queue:options: method on CBCentralManager which will cause iOS to start the Central Manager & not prompt the user to enable bluetooth. Voilla.. a totally passive way to check if bluetooth is enabled.

Note: The CBCentralManagerOptionShowPowerAlertKey was introduced in iOS 7