尝试从单独的 viewcontroller 更改 tableview 单元格标签时自定义委托方法调用两次

Question

我创建了一个自定义委托方法来更改表格视图单元格的标签文本，但该方法似乎被调用了两次。添加断点后，它似乎正在正确更改包含新标签文本的变量，但随后第二次调用它，这次变量为 nil。第二次调用改变了 label.text 但它为零。这是它的设置方式：

protocol ChangeInfoViewControllerDelegate {
    func changeInfoValue(vital: String)
}

//this class is where the new text value being created
class ManualVitalsInputViewController: UIViewController {

    let vitalVC = VitalsViewController()
    var delegate: ChangeInfoViewControllerDelegate!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.delegate = vitalVC
    }

    @IBAction func saveButtonTapped(_ sender: Any) {
        delegate.changeVitalValue(vital: "Test") //This gets called twice, 2nd time is nil
        dismiss(animated: true)
    }
}

//this is the controller where the text is being changed
class VitalsViewController: UIViewController {

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        let vital = vitals[indexPath.row]
        cell.imageView.image = vital.image

        if changedManualVital != nil {
            cell.vitalTitleLabel.text = changedManualVital//where text should change to new text from delegate
        } else {
            cell.vitalTitleLabel.text = vital.title
        }

        return cell
    }
}

//where delegate used
extension VitalsViewController: ChangeInfoViewControllerDelegate {

    func changeVitalValue(vital: String) {
        self.changedManualVital = vital
    }
}

关于委托被调用两次以及如何只调用一次的任何想法。或者，如果您有更好的建议来更改另一个表格视图单元格标签viewcontroller，我愿意接受建议。

Answer 1

你需要摆脱两者

let vitalVC = VitalsViewController()

和

 self.delegate = vitalVC

然后当你实例化手册时vc

 let vc = self.storyboard............... as! ManualVitalsInputViewController
 vc.delegate = self /// here is the actual link
 // present/push

尝试从单独的 viewcontroller 更改 tableview 单元格标签时自定义委托方法调用两次

Custom delegate method called twice when trying to change tableview cell label from separate viewcontroller

delegates

protocols

uitableview

ios

swift