20~21窗体弹出样式formSheet_关掉自动布局选iPad

1.菜单详情界面：
①xib 中设置为formSheet
②

    MainViewController *mainVC = [[MainViewController alloc]init];
    mainVC.modalPresentationStyle = UIModalPresentationFormSheet;
    mainVC.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    [self presentViewController:mainVC animated:YES completion:nil];

2.关掉自动布局：
重点：选iPad

然后详情弹出窗体背景图片才能正常显示