private void InitializePhoneApplication()
{
if (phoneApplicationInitialized)
return;
// 创建框架但先不将它设置为 RootVisual;这允许初始
// 屏幕保持活动状态,直到准备呈现应用程序时。
RootFrame = new PhoneApplicationFrame();
RootFrame.Navigated += CompleteInitializePhoneApplication;
// 处理导航故障
RootFrame.NavigationFailed += RootFrame_NavigationFailed;
// 在下一次导航中处理清除 BackStack 的重置请求,
RootFrame.Navigated += CheckForResetNavigation;
// 处理协定激活(如文件打开或保存选取器)
PhoneApplicationService.Current.ContractActivated += Application_ContractActivated;
// 确保我们未再次初始化
phoneApplicationInitialized = true;
}