你可以这样写

- (IBAction)showDetail:(UIButton *)sender {  
            DetailViewController *detailVc = [self.childViewControllers firstObject];  
        detailVc.lable.text = sender.titleLabel.text;  
    }  
}

如果有人正在寻找Swift 3.0，

viewController1, viewController2等等都是可访问的。

let viewController1 : OneViewController!
let viewController2 : TwoViewController!

// Safety handling of optional String
if let identifier: String = segue.identifier {

    switch identifier {

    case "segueName1":
        viewController1 = segue.destination as! OneViewController
        break

    case "segueName2":
        viewController2 = segue.destination as! TwoViewController
        break

    // ... More cases can be inserted here ...

    default:
        // A new segue is added in the storyboard but not yet including in this switch
        print("A case missing for segue identifier: \(identifier)")
        break
    }

} else {
    // Either the segue or the identifier is inaccessible 
    print("WARNING: identifier in segue is not accessible")
}

自我。当你需要父控件时，childViewControllers更相关。例如，如果子控制器是一个表视图，你想要强制重载它或通过点击按钮或父视图控制器上的任何其他事件来改变属性，你可以通过访问ChildViewController的实例来实现，而不是通过prepareForSegue。两者都有不同的应用方式。

在视图控制器的类型上使用Swift的switch语句还有另一种方法:

override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
  switch segue.destination
  {
    case let aViewController as AViewController:
      self.aViewController = aViewController
    case let bViewController as BViewController:
      self.bViewController = bViewController
    default:
      return
  }
}

你可以这样写

- (IBAction)showDetail:(UIButton *)sender {  
            DetailViewController *detailVc = [self.childViewControllers firstObject];  
        detailVc.lable.text = sender.titleLabel.text;  
    }  
}

你可以简单地使用self.childViewControllers.lastObject(假设你只有一个子对象，否则使用objectAtIndex:)。