使用swift做一个小的应用，调用showapi来显示笑话。

1.使用pod装第三方库，Alamofire请求http数据，SnapKit代码布局，SwiftJSON解析json；
pod文件：

platform :ios,'8.0'
use_frameworks!

target 'JokeText' do
  pod 'Alamofire','~> 3.0'
  pod 'SwiftyJSON',:git => 'https://github.com/SwiftyJSON/SwiftyJSON.git'
  pod 'SnapKit','~> 0.17.0'
end

2.打开Main.storyboard拖入一个TableView拉伸放置在合适的位置进行布局

3.关联UITableView
@IBOutlet weak var tableView: UITableView!

4.编写showapi（https://www.showapi.com/api/lookPoint/341/1）文本笑话请求，应答数据结构
1>请求：

//: Playground - noun: a place where people can play

//
// Request.swift
// JokeText
//
// Created by tutujiaw on 15/11/11.
// Copyright © 2015年 tujiaw. All rights reserved.
//

import Foundation

class Request {
    var appId: Int

    var timestamp: String {
        return NSDate.currentDate("yyyyMMddHHmmss")
    }

    var signMethod = "md5"

    var resGzip = 0

    var allParams = [(String,String)]()

    init(appId: Int) {
        self.appId = appId
    }

    func sign(appParams: [(String,String)],secret: String) -> String {
        self.allParams = appParams
        self.allParams.append(("showapi_appid",String(self.appId)))
        self.allParams.append(("showapi_timestamp",self.timestamp))

        let sortedParams = allParams.sort{$0.0 < $1.0}
        var str = ""
        for item in sortedParams {
            str += (item.0 + item.1)
        }
        str += secret.lowercaseString
        return str.md5()
    }

    func url(mainUrl: String,sign: String) -> String {
        var url = mainUrl + "?"
        for param in self.allParams {
            url += "\(param.0)=\(param.1)&"
        }
        url += "showapi_sign=\(sign)"
        return url
    }
}

//
// JokeTextRequest.swift
// JokeText
//
// Created by tutujiaw on 15/11/11.
// Copyright © 2015年 tujiaw. All rights reserved.
//

import Foundation

class JokeTextRequest : Request {
    var time: String = ""
    var page: Int = 0
    var maxResult: Int = 0

    var url: String {
        let params = [("time",self.time),("page",String(self.page)),("maxResult",String(self.maxResult))]
        let sign = super.sign(params,secret: "c7288cbf5a0941598e3ab326c27f9668")
        return super.url("https://route.showapi.com/341-1",sign: sign)
    }

    init(time: String = NSDate.currentDate("yyyy-MM-dd"),page: Int = 1,maxResult: Int = 20) {
        super.init(appId: 12078)
        self.time = time
        self.page = page
        self.maxResult = maxResult
    }
}

2>应答

//
// JokeTextResponse.swift
// JokeText
//
// Created by tutujiaw on 15/11/12.
// Copyright © 2015年 tujiaw. All rights reserved.
//

import Foundation
import SwiftyJSON

struct JokeItem {
    var title = ""
    var text = ""
    var ct = ""
}

class Response {

    static let sharedManager = Response()

    var resCode = -1
    var resError = ""
    var allNum = 0
    var allPages = 0
    var currentPage = 0
    var maxResult = 0
    var contentList = [JokeItem]()

    func setData(object: AnyObject) {
        let json = JSON(object)
        self.resCode = json["showapi_res_code"].int ?? -1
        self.resError = json["showapi_res_error"].string ?? ""

        let bodyJson = json["showapi_res_body"]
        self.allNum = bodyJson["allNum"].int ?? 0
        self.allPages = bodyJson["allPages"].int ?? 0
        self.currentPage = bodyJson["currentPage"].int ?? 0
        self.maxResult = bodyJson["maxResult"].int ?? 0

        if self.currentPage == 1 {
            self.contentList = [JokeItem]()
        }

        if let contentList = json["showapi_res_body"]["contentlist"].array {
            for content in contentList {
                guard let title = content["title"].string,let text = content["text"].string,let ct = content["ct"].string else {
                    continue
                }
                self.contentList.append(JokeItem(title: title,text: text,ct: ct))
            }
        }
    }
}

3>md5计算(http://www.jb51.cc/article/p-pcleyxep-te.html)

extension String {
    func md5() -> String! {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = CUnsignedInt(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen = Int(CC_MD5_DIGEST_LENGTH)
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
        CC_MD5(str!,strLen,result)
        let hash = NSMutableString()
        for i in 0..<digestLen {
            hash.appendFormat("%02x",result[i])
        }
        result.destroy()
        return String(format: hash as String)
    }
}

日期格式化

extension NSDate {
    static func currentDate(dateFormat: String) -> String {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = dateFormat
        dateFormatter.locale = NSLocale.currentLocale()
        return dateFormatter.stringFromDate(NSDate())

    }
}

5.自定义UITableViewCell

//
//  JokeViewCell.swift
//  JokeText
//
//  Created by tutujiaw on 15/11/14.
//  Copyright © 2015年 tujiaw. All rights reserved.
//

import UIKit
import SnapKit

class JokeViewCell : UITableViewCell {

    static let ID = "JOKE_VIEW_CELL_ID"

    let titleLabel = UILabel()
    let ctLabel = UILabel()
    let contentLabel = UILabel()

    override init(style: UITableViewCellStyle,reuseIdentifier: String?) {
        super.init(style: style,reuseIdentifier: reuseIdentifier)
        self.addSubview(titleLabel)
        self.addSubview(ctLabel)
        self.addSubview(contentLabel)

        titleLabel.textColor = UIColor.redColor()
        titleLabel.snp_makeConstraints{(make)->Void in
            make.top.equalTo(self.snp_top).offset(5)
            make.height.equalTo(20)
            make.left.equalTo(self.snp_left).offset(5)
            make.right.equalTo(ctLabel.snp_left).offset(-5)
        }

        ctLabel.textColor = UIColor.blueColor()
        ctLabel.snp_makeConstraints{(make)->Void in
            make.top.equalTo(self.snp_top).offset(5)
            make.height.equalTo(titleLabel)
            make.left.equalTo(titleLabel.snp_right).offset(5)
            make.width.equalTo(160)
            make.right.equalTo(self.snp_right).offset(-5)
        }

        contentLabel.snp_makeConstraints{(make)->Void in
            make.top.equalTo(titleLabel.snp_bottom).offset(5)
            make.bottom.equalTo(self.snp_bottom).offset(-5)
            make.centerX.equalTo(self.snp_centerX)
            make.width.equalTo(self).offset(-10)
        }
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

6.编写ViewController

//
//  ViewController.swift
//  JokeText
//
//  Created by tutujiaw on 15/11/11.
//  Copyright © 2015年 tujiaw. All rights reserved.
//

import UIKit
import Alamofire
import SnapKit

class ViewController: UIViewController {

    @IBOutlet weak var tableView: UITableView!
    var currentPage = 1
    var isLoading = false
    let refreshControl = UIRefreshControl()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view,typically from a nib.
        tableView.delegate = self
        tableView.dataSource = self
        tableView.estimatedRowHeight = 100
        tableView.rowHeight = UITableViewAutomaticDimension

        refreshControl.addTarget(self,action: "refreshData",forControlEvents: .ValueChanged)
        tableView.addSubview(refreshControl)

        requestData()
    }

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

    func getColor(color:Int32) -> UIColor{
        let red = CGFloat((color&0xff0000)>>16)/255
        let green = CGFloat((color&0xff00)>>8)/255
        let blue = CGFloat(color&0xff)/255
        return UIColor(red: red,green: green,blue: blue,alpha: 1)
    }

    func requestData() {
        print("----------\(currentPage)")
        let request = JokeTextRequest(time: "2015-01-01",page: currentPage)
        isLoading = true
        Alamofire.request(.GET,request.url).responseJSON { response in
            print(response.request?.URLString)
            if response.result.isSuccess {
                if let value = response.result.value {
                    Response.sharedManager.setData(value)
                    self.tableView.reloadData()
                }
            } else {
                response.result.error
            }
            self.isLoading = false
            self.refreshControl.endRefreshing()
        }
    }

    func refreshData() {
        currentPage = 1
        requestData()
    }
}

extension ViewController: UITableViewDelegate,UITableViewDataSource {

    internal func tableView(tableView: UITableView,numberOfRowsInSection section: Int) -> Int {
        return Response.sharedManager.contentList.count
    }

    internal func tableView(tableView: UITableView,cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        var cell = tableView.dequeueReusableCellWithIdentifier(JokeViewCell.ID) as? JokeViewCell
        if cell == nil {
            cell = JokeViewCell(style: .Subtitle,reuseIdentifier: JokeViewCell.ID)
        }

        let jokeItem = Response.sharedManager.contentList[indexPath.row]
        cell?.titleLabel.text = jokeItem.title
        cell?.ctLabel.text = jokeItem.ct.substringToIndex(jokeItem.ct.endIndex.advancedBy(-4))

        cell?.contentLabel.attributedText = NSAttributedString(string: jokeItem.text,attributes: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType])
        cell?.contentLabel.numberOfLines = 0
        cell?.contentLabel.preferredMaxLayoutWidth = CGRectGetWidth(tableView.bounds)
        return cell!
    }

    func tableView(tableView: UITableView,heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
        return UITableViewAutomaticDimension
    }

    func scrollViewDidScroll(scrollView: UIScrollView) {
        if self.isLoading {
            return
        }

        let space = CGFloat(10)
        let y = scrollView.contentOffset.y + scrollView.bounds.size.height - scrollView.contentInset.bottom
        //print("y:\(y),height:\(scrollView.contentSize.height),table height:\(self.tableView.frame.height)")
        if y > scrollView.contentSize.height + space {           // 滑到底部
            ++currentPage
            if currentPage > Response.sharedManager.allPages {
                currentPage = 1
            }
            requestData()
        }
    }

}

其中涉及到UITableView cell自适应高度（http://www.jb51.cc/article/p-dxbuaaev-te.html）