关于swift的协议

在viewController会显示 "Received message"

class ViewController:UIViewController,UITableViewDelegate,UITableViewDataSource
{
    var tableView :UITableView?
    var items :NSMutableArray?
    var leftBtn:UIButton?
    
    overridefunc viewDidLoad() {
        super.viewDidLoad()
        self.title ="I love Swift"
        self.items =NSMutableArray()
         self.items?.addObject("1")
        self.items?.addObject("2")
        self.items?.addObject("3")
        self.items?.addObject("4")
        self.items?.addObject("5")

        // Do any additional setup after loading the view,typically from a nib.
        setupViews()
        setupRightBarButtonItem()
        setupLeftBarButtonItem();
    }
    
    func setupViews()
    {
        self.tableView =UITableView(frame:self.view!.frame)
        self.tableView!.delegate =self
        self.tableView!.dataSource =self
        self.tableView!.registerClass(UITableViewCell.self,forCellReuseIdentifier: "cell")
        self.tableView?.separatorStyle=UITableViewCellSeparatorStyle.SingleLine;
        self.view.addSubview(self.tableView!)
    }
    
    func setupLeftBarButtonItem()
    {
        self.leftBtn =UIButton.init(type:UIButtonType.Custom)
        self.leftBtn!.frame =CGRectMake(0,50,40)
        self.leftBtn?.setTitleColor(UIColor.redColor(),forState: UIControlState.Normal)
        self.leftBtn?.setTitle("Edit",forState: UIControlState.Normal)
        self.leftBtn!.tag =100
        self.leftBtn!.userInteractionEnabled = false
        self.leftBtn?.addTarget(self,action: #selector(ViewController.leftBarButtonItemClicked),forControlEvents:UIControlEvents.TouchUpInside)
        let barButtonItem =UIBarButtonItem(customView:self.leftBtn!)
        self.navigationItem.leftBarButtonItem = barButtonItem
    }
    
    func setupRightBarButtonItem()
    {
        let barButtonItem =UIBarButtonItem(title: "Add",style: UIBarButtonItemStyle.Plain,target:self,action: #selector(ViewController.rightBarButtonItemClicked))
        self.navigationItem.rightBarButtonItem = barButtonItem
    }
    
    func rightBarButtonItemClicked()
    {
        
        let row =self.items!.count
        let indexPath =NSIndexPath(forRow:row,inSection:0)
        self.items?.addObject("1")
        self.tableView?.insertRowsAtIndexPaths([indexPath],withRowAnimation:UITableViewRowAnimation.Left)
        self.leftBtn!.userInteractionEnabled = true
    }
    
    func leftBarButtonItemClicked()
    {
        if (self.leftBtn!.tag == 100)
        {
            self.tableView?.setEditing(true,animated: true)
            self.leftBtn!.tag =200
            self.leftBtn?.setTitle("Done",forState: UIControlState.Normal)
        }
        else
        {
            self.tableView?.setEditing(false,animated: true)
            self.leftBtn!.tag =100
            self.leftBtn?.setTitle("Edit",forState: UIControlState.Normal)
        }
        
    }
    
    
    overridefunc didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    func tableView(tableView:UITableView,numberOfRowsInSection section:Int) -> Int
    {
        returnself.items!.count
    }
    
    func tableView(tableView:UITableView,cellForRowAtIndexPath indexPath:NSIndexPath) -> UITableViewCell
    {
        let cell = tableView .dequeueReusableCellWithIdentifier("cell",forIndexPath: indexPath) asUITableViewCell
        cell.textLabel!.text =String(format: "%i",indexPath.row+1)
        return cell
    }
    
    func tableView(tableView:UITableView,canEditRowAtIndexPath indexPath:NSIndexPath) -> Bool
    {
        returntrue
    }
    
    func tableView(tableView:UITableView,commitEditingStyle editingStyle:UITableViewCellEditingStyle,forRowAtIndexPath indexPath:NSIndexPath)
    {
        self.items?.removeObjectAtIndex(indexPath.row)
        
        self.tableView?.deleteRowsAtIndexPaths([indexPath],withRowAnimation:UITableViewRowAnimation.Top)
        if (self.items!.count == 0)
        {
            self.leftBtn!.userInteractionEnabled = false
        }
        
    }
    
    func tableView(tableView:UITableView,editingStyleForRowAtIndexPath indexPath:NSIndexPath) -> UITableViewCellEditingStyle
    {
        return (UITableViewCellEditingStyle.Delete)
    }
    
    func tableView(tableView:UITableView,canMoveRowAtIndexPath indexPath:NSIndexPath) -> Bool
    {
        returntrue
    }
    
    func tableView(tableView:UITableView,moveRowAtIndexPath sourceIndexPath:NSIndexPath,toIndexPath destinationIndexPath:NSIndexPath)
    {
        self.tableView?.moveRowAtIndexPath(sourceIndexPath,toIndexPath: destinationIndexPath)
        self.items?.exchangeObjectAtIndex(sourceIndexPath.row,withObjectAtIndex: destinationIndexPath.row)
    }
    
    func tableView(tableView:UITableView,didSelectRowAtIndexPath indexPath:NSIndexPath)
    {
        print("row = %d",indexPath.row)
    }
    
}

运行结果