What is the significance of the LDS claim that apostolic succession was lost till Joseph Smith was granted divine authority

I was recently in conversation with a lady who is a member of the Church of Jesus Christ of Latter-day Saints. She said they are the "true" church because apostolic authority was lost after the death of Jesus' 12 disciples, and that authority was not regained until Joseph Smith met with Moroni (son of Mormon). Reading the Introduction from The Book of Mormon, it says (in part): >The crowning event recorded in the Book of Mormon is the personal ministry of the Lord Jesus Christ among the Nephites soon after his resurrection... On September 21, 1823, the same Moroni, then a glorified, resurrected being, appeared to the Prophet Joseph Smith... Those who gain this divine witness from the Holy Spirit will also come to know by the same power that Jesus Christ is the Savior of the world, that Joseph Smith is his revelator and prophet in these last days, and that the Church of Jesus Christ of Latter-day Saints is the Lord's kingdom once again established on the earth, preparatory to the second coming of the Messiah. ***What I can't find are any official LDS statements to support her claim that apostolic authority was lost after the death of Jesus' 12 disciples, and that authority was not regained until Joseph Smith was given it by God.*** Before I can respond to this LDS lady I need more information on the LDS view of apostolic authority being granted to Joseph Smith.