ios CAAnimation  实现push效果显示模态控制器（presentViewController）

1，使用 CAAnimation 实现模态控制器的push效果，

// 要显示的控制器　　BusinessWebController * businessVC = [[BusinessWebController alloc] init];/*** addSubView的方式*///    　　[mainVC addChildViewController:businessVC];//        [mainVC.view addSubview:businessVC.view];///  在view的layer上 addAnimation （加 、 被加）//        [mainVC.view.layer addAnimation:transition forKey:nil];// 切换跟控制器的方式　　[UIApplication sharedApplication].keyWindow.rootViewController = businessVC;
    [UIApplication sharedApplication].keyWindow.backgroundColor = [UIColor whiteColor];// 构建push效果动画
        CATransition *transition = [CATransition animation];
        transition.duration = 0.15;
        transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
        transition.type = kCATransitionPush;
        transition.subtype = kCATransitionFromRight;
        transition.delegate = self;
        [businessVC.view.layer addAnimation:transition forKey:nil];