iOS7以下 window add view 转屏问题

[[UIApplication sharedApplication].delegate.window addSubview:view];

当使用上述代码加view时候，转屏，view不会自动转，解决方案如下：

UIWindow* window = [UIApplication sharedApplication].keyWindow;

    if (!window)

        window = [[UIApplication sharedApplication].windows objectAtIndex:0];

    [[[window subviews] objectAtIndex:0] addSubview:view];