遵守这个协议 NSURLSessionDownloadDelegate

        let url = NSURL(string:  urlString )
        let request = NSURLRequest(URL: url! )
        
        print("1")
        
        let config = NSURLSessionConfiguration.defaultSessionConfiguration()
        
        
        let session = NSURLSession(configuration: config , delegate: self , delegateQueue: NSOperationQueue.mainQueue() )
  
        
        let task = session.downloadTaskWithRequest(request)  用这个方法
//        let task = session.dataTaskWithRequest(request)  不要用这个方法

下一发

   override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        
        let titles = ["限免","降价","免费","专题","热榜"]
        //图片
        let images = ["tabbar_limitfree","tabbar_reduceprice","tabbar_appfree","tabbar_subject","tabbar_rank"]
        //选中时的图片
        let selectImages = ["tabbar_limitfree_press","tabbar_reduceprice_press","tabbar_appfree_press","tabbar_subject_press","tabbar_rank_press"]
        //视图控制器
        let controllers = [LimitFreeViewController() , ReduceViewController() , FreeViewController() , SubjectViewController() , RankViewController() ]
        
       
        var navigarionControllers = Array<UINavigationController>()
        
        for i in 0..<titles.count{
        
            
//            let ctrl = controllers[i]
//            print(ctrl.tabBarItem)
            
            controllers[i].tabBarItem.title = titles[i]
            
            controllers[i].tabBarItem.image = UIImage(named: images[i])?.imageWithRenderingMode(.AlwaysOriginal)
            
            
            
            controllers[i].tabBarItem.selectedImage = UIImage(named: selectImages[i] )?.imageWithRenderingMode(.AlwaysOriginal)
            
            
            
            let navigationCtrl = UINavigationController(rootViewController: controllers[i] )
            
            navigarionControllers.append(navigationCtrl)
            
            
        }
        
        
        self.viewControllers = navigarionControllers
        
        
        
        
        
    }
记得把图片
放到工程里。


因为
没加载
图片资源，
所以tabBarItem显示为空。
深刻滴感受到，
我是一个逗逼。