For unsigned applications, first enter the "Settings" menu of the mobile phone, then click "General" and then click "Device Management". In Device Management, locate the unsigned application, and then click Trust this application. This can solve the problem that some unsigned applications cannot be opened. If the problem still exists, you can try to download the application again to ensure that the download source is reliable and it is the official version. In addition, you can also consider updating Apple's mobile phone system to ensure the security and stability of the system. These methods can help solve the problem of unsigned applications.