In Leviticus 11:7 and Matthew 7:6, this signifies filthy loves of those in the hells of adulterers. (Apocalypse Explained 1044[4]) Swine signify people who love only worldly riches. (Apocalypse Revealed 727)

In Isaiah 65:4, this signifies appropriation of infernal evils. (Apocalypse Explained 659[2]) 'Swine' or 'hogs' correspond to the life of greed and its delight.

(References: Arcana Coelestia 1742)

617. 14:3 They sang as it were a new song before the throne, before the four living creatures, and before the elders. This symbolizes a celebration and glorification of the Lord in His presence and in the presence of the angels of the higher heavens.

Their singing a new song symbolizes an acknowledgment and glorification of the Lord as being the only Judge, Redeemer, and Savior, thus God of heaven and earth, as may be seen in no. 279 above. Before the throne means in the Lord's presence, because He alone sits upon the throne. Before the four living creatures and before the elders means in the presence of the angels of the higher heavens (no. 369).

As it were a new song symbolizes a celebration and glorification of the Lord in the New Christian Heaven. Here specifically it means that He was acknowledged as God of heaven and earth, as He is acknowledged in the ancient heavens. This is entailed in the phrase "as it were," for "as it were a new song" means that it was seemingly new, when in fact it was not new.

We have already said before that the new heaven spoken of in Revelation 21:1 is a new heaven formed of Christians, that the prior heavens were formed of ancient peoples and most ancient ones, and that in those heavens the Lord is acknowledged as God of heaven and earth.