Swift launchScreen改变之后APP没变 swift tabbarcontroller

上代码咯。。。。

import UIKit

class CustomTabBarBtn: UIButton {

    var mark:NSInteger = 0;

}

let SCREEN_W = UIScreen.mainScreen().bounds.size.width;
let SCREEN_H = UIScreen.mainScreen().bounds.size.height;
let TABBAR_H:CGFloat = 49.0;
let TABBAR_BTN_W = SCREEN_W / 5.0;
class MainViewController: UITabBarController {
    let backGroundImgV = UIImageView();

    override func viewDidLoad() {
        super.viewDidLoad()
        foreDeclare();
        creatTabBar();
    }

    private func foreDeclare() {

        tabBar.hidden = true;
        backGroundImgV.userInteractionEnabled = true;
    }

    func creatTabBar() {

        backGroundImgV.image = UIImage(named: "backgroundimage.png");
        backGroundImgV.frame = CGRect(x: 0, y: SCREEN_H - TABBAR_H, width: SCREEN_W, height: TABBAR_H);
        view.addSubview(backGroundImgV);

        for i in 0...4 {

            let tabBarButton = CustomTabBarBtn();
            tabBarButton.frame = CGRect(x: TABBAR_BTN_W * CGFloat(i), y: 0, width: TABBAR_BTN_W, height: TABBAR_H);
            tabBarButton.setBackgroundImage(UIImage(named: "tabbar_\(i)"), forState: .Normal);
            tabBarButton.setBackgroundImage(UIImage(named: "tabbar_selected_\(i)"), forState: .Selected);
            tabBarButton.addTarget(self, action: "itemClick:", forControlEvents: .TouchUpInside);
            tabBarButton.mark = i;
            if i == 1 {
                tabBarButton.selected = true;
            }
            backGroundImgV.addSubview(tabBarButton);

            let vc = UIViewController();
            vc.title = "页面\(i)";
            let nav = UINavigationController(rootViewController: vc);
            addChildViewController(nav);
        }

    }

    func itemClick(btn: CustomTabBarBtn) {
        selectedIndex = btn.mark;
        for tabbarBtn in backGroundImgV.subviews {
            let item = tabbarBtn as! CustomTabBarBtn;
            if item.mark == btn.mark {
                item.selected = true;
            }else {
                item.selected = false;
            }
        }
    }

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


    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

效果如下：