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.

(Odkazy: Arcana Coelestia 1742)

727. And pearls. This symbolizes the concepts of goodness and truth contained in the Word among Roman Catholics.

In the spiritual sense pearls symbolize concepts of both celestial and spiritual goodness and truth that come from the Word, in particular from its literal meaning; and because pearls symbolize those concepts, therefore they are mentioned after purple and scarlet and after gold and precious stones.

These concepts are symbolized by pearls also in the following passages:

...the kingdom of heaven is like a merchant seeking beautiful pearls, who, when he had found one pearl of great price, went and sold all that he had and bought it. (Matthew 13:45-46)

The pearl here symbolizes a concept of the Lord.

The twelve gates (in the wall of the New Jerusalem) were twelve pearls: each individual gate was of one pearl. (Revelation 21:21)

The gates of the New Jerusalem symbolize entrance into the New Church, and the entrance is made possible by concepts of goodness and truth from the Word.

Do not... cast your pearls before swine, lest they trample them under their feet, and... tear you in pieces. (Matthew 7:6)

Swine symbolize people who care only for worldly wealth, and not for spiritual wealth, namely for concepts of goodness and truth from the Word.

Because Babylon symbolizes a religion that has cast out all concepts of goodness and truth from the Word, we are told concerning it:

The merchants of the earth will weep and mourn over (Babylon), because no one buys their merchandise...: merchandise of gold and silver, precious stones, and pearls... (Revelation 18:11-12)