ios - UIViewController 在 vi​​ewDidLoad 之前访问 subview

Question

我有一个 UIViewController 的子类，我定义了一个这样的变量:

 public class CustomController: UIViewController {

    @IBOutlet weak var slider:UISlider!

     public var showSlider = false {
        didSet {       
          slider.isHidden = !showSlider
        }
      }
      ...
      ...
  }

现在，如果我像这样实例化我的自定义 View Controller :

  let controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "CustomController") as! CustomController

  controller.showSlider = true

问题是第二行甚至可能在 viewDidLoad 或 IBOutlets 设置之前被调用。遇到这种情况怎么办？

Answer 1

当前代码会在您访问 outlet 之前崩溃，因此您需要 loadViewIfNeeded

let controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "CustomController") as! Cust   omController 
controller.loadViewIfNeeded()
controller.showSlider = true