winrt代码获取datatemplate中的控件

此方法会递归遍历该DependencyObject的所有VisualChildren（一般用于获取template中未知Name属性但已知类型的控件）：

 public static ChildControl FindVisualChild<ChildControl>(this DependencyObject DependencyObj)
                 where ChildControl : DependencyObject
        {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(DependencyObj); i++)
            {
                DependencyObject Child = VisualTreeHelper.GetChild(DependencyObj, i);

                if (Child != null && Child is ChildControl)
                {
                    return (ChildControl)Child;
                }
                else
                {
                    ChildControl ChildOfChild = FindVisualChild<ChildControl>(Child);

                    if (ChildOfChild != null)
                    {
                        return ChildOfChild;
                    }
                }
            }

            return null;
        }

此方法可获取指定Name属性的子控件（一般用于获取容器控件中已知Name属性的子控件）：

        public static T GetNamedDescendantOfType<T>(this DependencyObject start, string name) where T : FrameworkElement
        {
            var descendants = start.GetDescendants();
            if (descendants != null)
            {
                foreach (FrameworkElement d in descendants)
                {
                    if (d.Name.Equals(name))
                        return d as T;
                }
            }

            return null;
        }

        public static IEnumerable<DependencyObject> GetDescendants(this DependencyObject start)
        {
            var queue = new Queue<DependencyObject>();
            var count = VisualTreeHelper.GetChildrenCount(start);

            for (int i = 0; i < count; i++)
            {
                var child = VisualTreeHelper.GetChild(start, i);
                yield return child;
                queue.Enqueue(child);
            }

            while (queue.Count > 0)
            {
                var parent = queue.Dequeue();
                var count2 = VisualTreeHelper.GetChildrenCount(parent);

                for (int i = 0; i < count2; i++)
                {
                    var child = VisualTreeHelper.GetChild(parent, i);
                    yield return child;
                    queue.Enqueue(child);
                }
            }
        }