Alamofire.request("https://httpbin.org/get", method: .GET)
    .responseJSON().then { json, rsp in
        // 
    }.catch{ error in
        //…
    }

func login() -> Promise<User> {
    let q = DispatchQueue.global()
    UIApplication.shared.isNetworkActivityIndicatorVisible = true

    return firstly { in
        Alamofire.request(url, method: .get).responseData()
    }.map(on: q) { data, rsp in
        convertToUser(data)
    }.ensure {
        UIApplication.shared.isNetworkActivityIndicatorVisible = false
    }
}

firstly {
    login()
}.done { user in
    //…
}.catch { error in
   UIAlertController(/*…*/).show() 
}

// `.swift` files
import PromiseKit
import Alamofire

// `.swift` files
import PromiseKit
import PMKAlamofire

let package = Package(
    dependencies: [
        .Target(url: "https://github.com/PromiseKit/PMKAlamofire", majorVersion: 5)
    ]
)