ios - Monotouch 导入联系人 - 返回类型问题

Question

如果他们被选中，我试图让这个方法返回一个人。我的问题是我收到一条错误消息，指出委托(delegate)不能返回 void 以外的类型，这很烦人，因为我不希望此方法返回，除非这两个操作之一发生。有什么建议吗？

public static ABPerson ImportContact ()
        {
            // Create placeholder for contact
            ABPeoplePickerNavigationController _contactController = new ABPeoplePickerNavigationController ();
            AppDelegate.navigation.PresentViewController (_contactController, true, null);

            _contactController.Cancelled += delegate {
                AppDelegate.navigation.DismissViewController (true, null);
                return;
            };

            _contactController.SelectPerson += delegate(object sender, ABPeoplePickerSelectPersonEventArgs e) {
                _importedContact = e.Person.GetEmails().FirstOrDefault;
                AppDelegate.navigation.DismissViewController (true, delegate {
                    return e.Person;
                });
            };
        }

Answer 1

您试图在内部委托(delegate)方法中返回函数结果。实现起来是不可能的。尝试改用公共(public)事件。即:

    public event Action<ABPerson> OnPersonSelect;
    public void ImportContact ()
    {
        // Create placeholder for contact
        ABPeoplePickerNavigationController _contactController = new ABPeoplePickerNavigationController ();
        NavigationController.PresentViewController (_contactController, true, null);

        _contactController.Cancelled += delegate {
            NavigationController.DismissViewController (true, null);
            return;
        };

        _contactController.SelectPerson += delegate(object sender, ABPeoplePickerSelectPersonEventArgs e) {
            var _importedContact = e.Person;
            NavigationController.DismissViewController (true, delegate {
                if (OnPersonSelect != null)
                {
                    OnPersonSelect(_importedContact);
                }
            });
        };
    }

请注意，我将此方法标记为非静态的，以便在我自己的测试示例中使用它。