I've read that whenever Jesus or the Apostles refer to the end times (prior to 70 AD) they are referring to the destruction of the Temple by Titus in 70 AD. But I've also read that Jesus and the apostles are referring to the apocalypse as written in Revelation. What does the Catholic Church teach on this issue?
Despite the problem I have trying to link what Jesus said about 'the end times' with whether the Catholic Church says he meant the destruction of the temple or the apocalypse, I will attempt a partial answer.
Yes, Jesus prophesied Jerusalem's huge temple stones would be cast down in Matthew 24:1-2, nearly 40 years before that happened. Yet it was only with hindsight that the Apostles could understand that. It is of immense significance that no writer of the New Testament spoke of that destruction as having happened, and Jesus never gave any dates for when that would happen. He only spoke of "this generation". Yet none of the NT writers went on about that, trying to anticipate when the temple's destruction would happen. They were concerned to write about Jesus returning in glory to bring in the end of all things, not just one building, or one city!
Given that the only book of the NT that was written after AD 70 was the Revelation given to a 90-year-old John, and not even he mentioned Titus, or the temple's destruction, or the date involved, we need to ask why there's such glaring omission. Yes, some propose the idea that the AD 70 destruction is hinted at in the Book of the Revelation. But a huge fact about that book is that it starts with the risen Christ telling the aged John that what he is going to show John are "things which must shortly come to pass" (Rev. 1:1). Future tense, not past tense! AD 70 was in the past.
The Apocalypse (another title some use for the Book of the Revelation) is another huge clue. Catastrophic events are detailed; plagues poured out from heaven onto an ungodly world, culminating in the sixth seal being opened in heaven, which results in the heavens departing as a scroll slamming shut, with every island and mountain moved out of its place (Rev.6:12-14 & 16:20). The first heaven and the first earth pass away, and God creates a new heaven and a new earth (Rev.21:1). The end, or the apocalypse, detailed in the Book of the Revelation is a message given by Christ, from God, via an angel. Anything that happened in AD 70 to one temple and one city pales into a fleeting detail of history compared with what Jesus says will happen globally, leading up to his spectacular return to earth.
The Christian Church was clear about that once the Book of the Revelation had been given to her, near the end of the first century. She knew that Jesus had accurately prophesied the AD 70 destruction by Titus, without any mention in the NT about that date or that person. She also knew that such a prophesy at the start of Matthew chapter 24, having been fulfilled, gave her confidence that the still-to-come future prophesies about global events building up to Christ's return in the book sometimes called 'The Apocalypse' would also be fulfilled. And Matthew 24, read with benefit of having read that last book of prophesy decades later, confirms Jesus having both foretold the destruction of AD 70 and a much later, global destruction at 'the last trump', in the last hour of the last day.
It's not an 'either', 'or' choice that has to be made here; it's both being equally true! In Matthew chapter 24 he refers to both; in the Revelation he details still future events, as the first verse makes clear: "To show unto his servants things which must shortly come to pass" - written at least two decades after the destruction of Jerusalem's temple.