I am using a HM-10 bluetooth to pair with my iPhone but I noticed that HM-10 can't be paired with iPhone using the "settings". It just won't show up in my bluetooth list. I will need a special app like "Lightblue" or "Bluecap" to pair it.
My question is, if I need a certain app to pair the bluetooth module with my iPhone, why is that many devices such as bluetooth speakers could be paired using the "settings" even without having an app?
Are there any bluetooth modules that could be paired without having an app like "Lightblue" or "Bluecap"?
Pairing through settings is only available for devices that use legacy profiles such as handsfree or A2DP.
Bluetooth Low Energy devices, such as the HM-10 are discoverable by any app using Core Bluetooth. Apps, like LightBlue, are just general purpose BLE apps that let you explore available BLE devices.
BLE devices only require pairing if they are using encryption on their characteristics. In this case, iOS will show the pairing dialog and complete the pairing process when the app attempts to read the encrypted characteristic.
To use the HM-10 you will need to write your own app to perform whatever communication task you are trying to achieve.