In iOS 11 Control Center has a button to disable Wi-Fi and Bluetooth networks. However, even if the user has turned off Bluetooth and Wi-Fi through the Control Center, it turns the radio from the iPhone will remain on.
Apple keeps Wi-Fi and Bluetooth radios running in the background to ensure certain features are still running, such as AirDrop's file transfer feature, geolocation feature and connection with Apple Watch. This changes the functionality of the Wi-Fi and Bluetooth buttons from the previous one.
Indeed this can help the user to avoid inadvertently disconnecting with Apple Watch or turn off various functions on the iPhone. The bad thing is, this means, the iPhone will be more vulnerable to cyber attacks.
Security researcher Andrea Barisani, who realizes this has been discussing it on Twitter. On the motherboard, he said, if the user is worried about cyber attacks, turning off the Bluetooth connection and Wi-Fi is a wise move. In addition, turn off the Bluetooth connection and Wi-Fi can also make the phone battery last longer.
If you want to turn Wi-Fi and Bluetooth off on iOS 11, you have to go to the Settings menu and disable it manually.
For Apple that prides itself on simple designs and interfaces, these changes can be bad, as it makes users think their Wi-Fi and Bluetooth phones are in a state of inactivity.