UDIDs

udid (unique device identifier) is a unique alphanumeric code assigned to each ios device in the context of ad hoc provisioning profiles for ios apps, udids are used to specify the devices on which the app can be installed and tested outside of the app store by including the udids of specific devices in the ad hoc provisioning profile, you restrict the installation and execution of the app to those devices only this allows you to distribute the app to a limited group of testers for testing purposes without submitting it to the app store once you have copied the udid, you can then share it with developers or use it for any purposes that require it, such as device registration for beta testing apps remember to keep your udid private and only share it with trusted parties find out the udid of your mobile device using itunes (on a computer) connect your ios device to your computer using a usb cable open itunes (if it doesn't open automatically) select your device icon in the upper left corner of the itunes window in the summary tab, you should see information about your device click on the serial number it will change to the udid right click on the udid and select "copy" to copy it to your clipboard using finder (on macos catalina and later) connect your ios device to your mac using a usb cable open finder (if it doesn't open automatically) in the sidebar, under locations, you should see your ios device click on your device to reveal its details in the general tab, you'll see details about your device including the serial number click on the serial number it will change to the udid right click on the udid and select "copy" to copy it to your clipboard using third party apps there are also third party apps available on the app store that can help you find your device's udid simply search for "udid" in the app store, and you'll find several apps that can display your udid directly on your device without needing a computer collect udids to distribute your app for ad hoc testing, you need to obtain the udids of the devices on which you want to install and test the app the udid can be obtained by connecting the device to a computer with itunes or by using third party tools or services add udids to the apple developer account in the 'devices" section of your apple developer account, you will have the option to add the devices (identified by their udids) that will be included in the adhoc provisioning profile of your future test app