PresentViewController 在 instantiateViewController 上发现 nil 值

Question

 func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if collectionView.tag == 2{

            switch indexPath.item {
            case 0:
               if let vc = storyboard?.instantiateViewController(withIdentifier: "offersScreen") as? OffersVC {
                vc.cityID = self.cityID!
                vc.categoryID = indexPath.item + 1
                vc.headingLBL.text =  self.names[indexPath.item]
                vc.cityLBL.text = self.selectCity.text!
                    present(vc, animated: true, completion: nil)
                }   
            case 1:
                print("You're heading VC 1!")
            case 2:
                print("You're heading VC 2!")
            case 3:
                print("You're heading VC 3!")
            default:
                print("Something went wrong")
            }
        }
    }

enter image description here

我写的一切都很完美，我知道我犯了什么错误。它发现 on present 没有价值。我从标签栏 viewController 中显示 viewcontroller 有 4 个值请帮助或指导。提前致谢。

Answer 1

原因是在 vc 加载

之前所有插座都为零

选项#1

 vc.loadViewIfNeeded()
 vc.headingLBL.text =  self.names[indexPath.item]

选项#2

为您需要发送的内容制作变量

class OffersVC:UIViewController {
   var sendedStr = ""

然后里面viewDidLoad

self.headingLBL = sendedStr

Answer 2

查看您的图像描述，我认为问题在于您试图在未先初始化的情况下展开 'headingLBL'。

见

PresentViewController 在 instantiateViewController 上发现 nil 值

PresentViewController found nil value on instantiateViewController

storyboard

uiviewcontroller

presentviewcontroller

swift