Creating multiple tableViews in one ViewController...this just starts out as a view controller

twotableviewsInOneView.swift

//
//  ViewController.swift
//  Delete
//
//  Created by Mike Chirico on 10/21/15.
//  Copyright © 2015 Mike Chirico. All rights reserved.
//

import UIKit

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
    
    
    @IBOutlet weak var tableView: UITableView!
    @IBOutlet weak var tableView1: UITableView!
    
    /// A simple data structure to populate the table view.
    struct PreviewDetail {
        let title: String
        let preferredHeight: Double
    }
    
    let sampleData = [
        PreviewDetail(title: "Small", preferredHeight: 160.0),
        PreviewDetail(title: "Medium", preferredHeight: 320.0),
        PreviewDetail(title: "Large", preferredHeight: 0.0) // 0.0 to get the default height.
    ]
    
    let sampleData1 = [
        PreviewDetail(title: "One", preferredHeight: 160.0),
        PreviewDetail(title: "Two", preferredHeight: 320.0),
        PreviewDetail(title: "Three", preferredHeight: 0.0), // 0.0 to get the default height.
        PreviewDetail(title: "More", preferredHeight: 0.0) // 0.0 to get the default height.
    ]
    
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        
        tableView.dataSource = self
        tableView.delegate = self
        tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: "cell")
        
        tableView1.dataSource = self
        tableView1.delegate = self
        tableView1.registerClass(UITableViewCell.self, forCellReuseIdentifier: "cell1")
        
        
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    
    
    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        // Return the number of items in the sample data structure.
        
        var count:Int?
        
        if tableView == self.tableView {
            count = sampleData.count
        }
        
        if tableView == self.tableView1 {
            count =  sampleData1.count
        }
        
        return count!
        
    }
    
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        
        var cell:UITableViewCell?
        
        if tableView == self.tableView {
            cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath)
            let previewDetail = sampleData[indexPath.row]
            cell!.textLabel!.text = previewDetail.title
            
        }
        
        if tableView == self.tableView1 {
            cell = tableView.dequeueReusableCellWithIdentifier("cell1", forIndexPath: indexPath)
            let previewDetail = sampleData1[indexPath.row]
            cell!.textLabel!.text = previewDetail.title
            
        }
        
        
        
        return cell!
    }
    
    
    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        print("did select:      \(indexPath.row)  ")
     }
    
    
    
}

You saved my life

I would strongly discourage making your main tableview-owning ViewController conform to UITableViewDataSource and UITableViewDelegate like this, if you want to drive multiple tables.

The fact that you have branching logic in your data source methods like if tableView == self.tableView { is an indication that you have two conjoined twin objects that are trying to get out.

Make two separate data source objects, and let them each focus on one of the two data sets, without any branching like this.