Connect to a WIFI hotspot programmatically in iOS 11

NEHotspotConfigurationManager.swift

//
//  ViewController.swift
//  NetworkTest
//
//  Created by Kraig Spear on 10/10/17.
//  Copyright © 2017 spearware. All rights reserved.
//

import UIKit
import NetworkExtension

final class ViewController: UIViewController {

	private let SSID = ""
	
	override func viewDidLoad() {
		super.viewDidLoad()
		// Do any additional setup after loading the view, typically from a nib.
	}

	@IBAction func connectAction(_ sender: Any) {
		let hotspotConfig = NEHotspotConfiguration(ssid: SSID, passphrase: "", isWEP: false)
		
		NEHotspotConfigurationManager.shared.apply(hotspotConfig) {[unowned self] (error) in
			
			if let error = error {
				self.showError(error: error)
			}
			else {
				self.showSuccess()
			}
		}
	}
	
	@IBAction func disconnectAction(_ sender: Any) {
		NEHotspotConfigurationManager.shared.removeConfiguration(forSSID: SSID)
	}
	
	private func showError(error: Error) {
		let alert = UIAlertController(title: "Error", message: error.localizedDescription, preferredStyle: .alert)
		let action = UIAlertAction(title: "Darn", style: .default, handler: nil)
		alert.addAction(action)
		present(alert, animated: true, completion: nil)
	}
	
	private func showSuccess() {
		let alert = UIAlertController(title: "", message: "Connected", preferredStyle: .alert)
		let action = UIAlertAction(title: "Cool", style: .default, handler: nil)
		alert.addAction(action)
		present(alert, animated: true, completion: nil)
	}
	
	
	
}

Turn on both Network Extensions & Hotspot Configuration Capabilities

I was looking at how to use NEHotspotConfiguration here, and that listed a reference to "kraigspear’s GIST"... Always happy to run into your code. : D

I know this is kinda old but I just wanted to add something so people that stumble upon this don't get confused in the future.

If the error is nil in the callback it does not mean you are connected. It means the configuration was added successfully.
From the documentation in NetworkExtension/NEHotspotConfigurationManager.h:

@param completionHandler A block that will be called when add/update operation is completed.
This could be nil if application does not intend to receive the result.
The NSError passed to this block will be nil if the configuration is successfully stored, non-nil otherwise.
If the configuration is found invalid or API encounters some other error then completionHandler is called
with instance of NSError containing appropriate error code. This API attempts to join the Wi-Fi network
if the configuration is successfully added or updated and the network is found nearby.

The interesting part is The NSError passed to this block will be nil if the configuration is successfully stored, non-nil otherwise.
The completionhandler gets called before the connection is actually established.
You have to check if the SSID changed to the expected one yourself afterwards.