实现iOS启动页淡出效果

先上Demo：https://github.com/w11p3333/LaunchDemo

思路：将launchScreen作为window的一个addsubview

实现：
1.在LaunchScreen中将Storyboard ID设置为Launch
2.实现方法

private func launchAnimation()
   {

   let vc = UIStoryboard(name:"LaunchScreen", bundle:nil).instantiateViewControllerWithIdentifier("Launch")
   let launchview = vc.view
   let delegate = UIApplication.sharedApplication().delegate
   let mainWindow = delegate?.window
   mainWindow!.addSubview(launchview)
   UIView.animateWithDuration(1, delay: 0.5, options: UIViewAnimationOptions.BeginFromCurrentState, animations: {
   launchview.alpha = 0.0
   launchview.layer.transform = CATransform3DScale(CATransform3DIdentity, 1.5, 1.5, 1.0)
   }) { (finished) in
   launchview.removeFromSuperview()
   }
     }

若是应用使用storyboard中加载的，需要在初始界面的viewcontroller的viewDidAppear方法中调用。

若是应用从代码中加载的，需要在AppDelegate中didFinishLaunchingWithOptions方法中调用