模拟按Home键退出应用的方法

func exitApplication() {
        let app = UIApplication.sharedApplication().delegate as! AppDelegate
        let window = app.window
        dispatch_async(dispatch_get_main_queue(), {
            UIView.animateWithDuration(0.5, animations: {
                window!.alpha = 0
                window?.frame = CGRectMake((window?.bounds.size.width)!/2.0, (window?.bounds.size.height)!/2.0, 0, 0)
            }) { (finish) in
                exit(0)
            }
        })
    }