When will the value of the IDFA change?

Under what circumstances will the IDFA value of the application change?

Recently, we need to get an ID that uniquely identifies each of the different apps, and the previous Apple Udid is no longer available, so we need to use the new IDFA to refer to it. But in some cases this ID number will be modified (to become the new value), then what is the case? Let's take a look at each of them.

• Select "Reset all Settings" in the iOS settings app
  * No impact

• "Clear all content and Settings" in iOS Settings app
  * advertisingIdentifier and identifierForVendor will be affected re-set to new value

• Restore your device from itunes
  * advertisingIdentifier and identifierForVendor will be affected re-set to new value

• Remove the app from your device
  * If the app is the last app on the device under a developer account, it will affect identifierForVendor the value, otherwise it will not affect the value of the field.

• Upgrade your App
  * No impact

• Turn limit ad tracking on or off
  * advertisingIdentifier The specific value of the field should be affected

• System upgrade (upgrade via your phone or via itunes)
  * Will change identifierForVendor the value of the field

• "Reset ad Identifiers" in iOS settings app
  * Will change advertisingIdentifier the value. If some apps are requesting the field, the value of the field will not change until the app restarts.

• Back up with itunes
  * No effect on these two fields

• Restore a backup from itunes
  * Two fields will be reset

When will the value of the IDFA change?