The minimal stuff you need to search for BLE devices in macOS

BLEFinder.swift

//Copyright 2019 Dalton Durst
//
//Permission is hereby granted, free of charge, to any person obtaining a copy
//of this software and associated documentation files (the "Software"), to deal
//in the Software without restriction, including without limitation the rights
//to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//copies of the Software, and to permit persons to whom the Software is
//furnished to do so.
//
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//SOFTWARE.

import Cocoa
import CoreBluetooth

class BLEFinder: NSObject, CBCentralManagerDelegate {
    
    override init() {
        super.init()
        centralManager = CBCentralManager(delegate: self, queue: nil)
    }
    
    func begin() {
        centralManager.scanForPeripherals(withServices: nil, options: nil)
    }
    
    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        print("state: \(central.state.rawValue)")
        begin()
    }
    
    func connectTo(peripheral: CBPeripheral) {
        self.peripheral = peripheral
    }
    
    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        print("Found peripheral! \(peripheral)")
        connectTo(peripheral: peripheral)
    }
    
    var centralManager: CBCentralManager!
    var peripheral: CBPeripheral?
}

var stuff = BLEFinder()

You may be more interested in https://gist.github.com/UniversalSuperBox/4240dca31984afda7028a7c3d522cde5, which expands on this file.