winform恢复窗口前端显示

[DllImport("user32.dll")]
public static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab);

Process instance = null;
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);
//遍历与当前进程名称相同的进程列表
foreach (Process process in processes)
{
　　//如果实例已经存在则忽略当前进程
　　if (process.Id != current.Id)
　　{
　　　　//得到已经存在的进程
　　　　instance = process;
　　　　break;
 　　}
}

Process instance = Process.GetCurrentProcess();

SwitchToThisWindow(instance.MainWindowHandle, true);