ios - 如何将对对象的引用传递给导航 Controller 中包含的模态呈现的 View Controller ？

Question

我在传递对我的数据对象的引用时遇到问题。呈现 View Controller 具有对数据对象的引用。模态视图 Controller 连接到导航 Controller ，并且是它的 Root View Controller 。这是我的做法:

展示 VC:

- (IBAction)changeCustomerButtonPress:(UIButton *)sender {    
    UINavigationController *customersNC = [self.storyboard instantiateViewControllerWithIdentifier:@"customersNC"];
    SCCustomersVC *customersVC = (SCCustomersVC *)[self.storyboard instantiateViewControllerWithIdentifier:@"customersVC"];
    customersVC.dataObject = self.splitVC.dataObject;

    //at this point, customersVC.dataObject exists

    [self presentViewController:customersNC animated:YES completion:nil];
}

出现模态VC时，self.dataObject为nil。

- (void)viewWillAppear:(BOOL)animated
{       
    //self.dataObject is nil here.
}

正确的做法是什么？

Answer 1

IB 中的导航 Controller 是否有 Root View Controller ？如果，不应该。但是假设您有一个，您不应该实例化 SCCustomersVC，因为导航 Controller 将在实例化时执行该操作。要传递数据，只需使用 topViewController 获取对该 Controller 的引用:

SCCustomersVC *customersVC = (SCCustomersVC *)[customerNC topViewController];
    customersVC.dataObject = self.splitVC.dataObject;