Question

假设我有3个视图控制器：A，B和C.并且我有3个段：A-> B，B-> C，C-> B。我正在使用委托将几个值从A传递给B，这样我就可以在B VC中填充标签文本，一切都很好。然后我从B到C，这很好。但是当我从C回到B时，我有错误说委托值是零。在进入C并返回B后，如何保持VC B中VC A的值？对不起，如果它太混乱或者太简单了，我还是初学者。谢谢你的帮助。

修改

HomeViewController（A）

 public string Page()
    {
        string page_ = "";

        try
        {
            SqlCommand cmd = new SqlCommand();
            SqlConnection conn = new SqlConnection();
            conn.ConnectionString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
            cmd.CommandText = "sp_master";
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Connection = conn;
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                ["Name"], Sp_details = dt.Rows[i]["Sp_details"], Html_Links=dt.Rows[i]["Html_Links"] ,status = dt.Rows[i]["status"] });

                page_ = page_ + "<li><a onclick='menu(" + dt.Rows[i]["Sp_details"] + ")'>" + dt.Rows[i]["ReportName"] + "</a></li>";
            }

        }
        catch (Exception)
        {
            throw;
        }
        return page_;
    }

RecipeDetailVC（B）

protocol recipeDetailVariables 
{

    var recipes:[String] { get set }
    var recipeDescription: [String] { get set }
    var indexPathRow: Int {get set}

}

protocol recipeDetailVCDelegate {

    var delegate: recipeDetailVariables! { get set }

}
class HomeViewController ...
[...]

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if (segue.identifier == "segueRecipeDetail") {

            let destination = segue.destination as! RecipeDetailVC

            destination.delegate = self


        }

Ps：到目前为止一切都很好

RecipeReviewVC（C）

有一个segue via storyboard通过bar按钮带到这个VC，另一个segue返回RecipeDetailVC。当我返回RecipeDetailVC时，它在class RecipeDetailVC[...] override func viewDidLoad() { super.viewDidLoad() self.recipeTitle.text = delegate?.recipes[delegate.indexPathRow] self.recipeInstructions.text = delegate?.recipeDescription[delegate.indexPathRow] }行失败，说它没有

SWIFT - 在segue和return之后保留委托值

0 个答案: