Register readers
Register your readers to a location.
You must register your reader to a location to accept payments. The process for registering your reader to a location differs based on whether it’s a smart reader or a mobile reader.
Smart readers 
Registration code
For this method, you must generate a pairing code (also known as a registration code) on the reader. If a reader isn’t registered, a pairing code automatically appears on the screen when you unbox it. If it isn’t, or if you need to re-register a reader, you can generate a new pairing code using the admin settings. After generating the pairing code, you can enter it in the Dashboard or API to register the reader.
Use the Reader API to register a reader with a pairing code.
curl https://api.stripe.com/v1/terminal/readers \
-u "sk_test_4eC39HqLyjWDarjtT1zdp7dc
Mobile readers
Register mobile readers (Stripe Reader M2, BBPOS Chipper 2X BT, and BBPOS WisePad 3) to a location while connecting to the reader by specifying the locationId in your BluetoothConnectionConfiguration. If you prefer, you can register the reader to the last used location by passing in the reader.locationId from a discovered reader.
let connectionConfig: BluetoothConnectionConfiguration
do {
connectionConfig = try BluetoothConnectionConfigurationBuilder(delegate: yourMobileReaderDelegate, locationId: )
.build()
} catch {
return
}
Terminal.shared.connectReader(selectedReader, connectionConfig: connectionConfig) { reader, error in
if let reader = reader {
print("Successfully connected to reader: \(reader)")
} else if let error = error {
print("connectReader failed: \(error)")
}
}