Primer paso, crear archivo Popfile con el siguiente contenido:

source 'https://github.com/CocoaPods/Specs.git'
use_frameworks!

target 'SaldoTUC', :exclusive => true do
  pod 'LiquidFloatingActionButton', :git => 'https://github.com/yoavlt/LiquidFloatingActionButton.git', :branch => 'swift-2.0'
end

Ahora ejecuta:

$ pod install

Si aun no tienes instalado CocoaPod aqui estan las indicaciones: https://guides.cocoapods.org/using/getting-started.html

En el archivo ViewController.swift debera quedar asi:

//
//  ViewController.swift
//  SaldoTUC
//
//  Created by McNally Paulo on 3/12/15.
//  Copyright © 2015 Chocoyo Labs. All rights reserved.
//

import UIKit
import LiquidFloatingActionButton

class ViewController: UIViewController, LiquidFloatingActionButtonDataSource, LiquidFloatingActionButtonDelegate {

    var cells: [LiquidFloatingCell] = []
    var floatingActionButton: LiquidFloatingActionButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        //        self.view.backgroundColor = UIColor(red: 55 / 255.0, green: 55 / 255.0, blue: 55 / 255.0, alpha: 1.0)
        // Do any additional setup after loading the view, typically from a nib.
        let createButton: (CGRect, LiquidFloatingActionButtonAnimateStyle) -> LiquidFloatingActionButton = { (frame, style) in
            let floatingActionButton = LiquidFloatingActionButton(frame: frame)
            floatingActionButton.animateStyle = style
            floatingActionButton.dataSource = self
            floatingActionButton.delegate = self
            return floatingActionButton
        }


        let floatingFrame = CGRect(x: self.view.frame.width - 56 - 16, y: self.view.frame.height - 56 - 16, width: 56, height: 56)
        let bottomRightButton = createButton(floatingFrame, .Up)


        self.view.addSubview(bottomRightButton)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func numberOfCells(liquidFloatingActionButton: LiquidFloatingActionButton) -> Int {
        return cells.count
    }

    func cellForIndex(index: Int) -> LiquidFloatingCell {
        return cells[index]
    }

    func liquidFloatingActionButton(liquidFloatingActionButton: LiquidFloatingActionButton, didSelectItemAtIndex index: Int) {
        liquidFloatingActionButton.close()
    }

}

Recursos: