When deactivating an app, AltStore will first install AltBackup in its place. This allows AltBackup to access the (soon to be) inactive app’s sandbox, and backup all files to a shared app group with AltStore. Later when activating, AltStore will again install AltBackup and use it to restore files before installing the actual app again.
AltStore now inserts an app-specific UTI when resigning apps, and it periodically checks whether that app has been deleted by checking whether UTTypeCopyDeclaration returns nil for the same app-specific UTI.
