无法通过 Delegate/Protocol 访问 parent VC 中的 func()

Question

无法通过 delegate/protocol 从 child 访问 parent 视图控制器中的功能。 print() 不打印。

在 Child VC 我有这个：

protocol MyViewControllerDelegate: class {
    func requestExpandedView()
}
    
class MyViewController: UIViewController {
        
    weak var delegate: MyViewControllerDelegate?
    ...

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        print("\(indexPath) didSelectItemAt")
        
        delegate?.requestExpandedView()  
    }
}

在 Parent VC 我有这个：

extension MessagesViewController: MyViewControllerDelegate {
    func requestExpandedView() {
        print("Done") // doesn't print anything
        requestPresentationStyle(.expanded)
    }
}

怎么了？

Answer 1

创建实例时需要设置MyViewController的delegate，即

let vc = self.storyboard?.instantiateViewController(withIdentifier: "MyViewController") as! MyViewController
vc.delegate = self

无法通过 Delegate/Protocol 访问 parent VC 中的 func()

Can't access to func() in parent VC via Delegate/Protocol

swift

delegates

protocols

imessage-extension