As for swift - you need to resort to custom scripts from AUR
And due to compatibility issues on Manjaro stable branch - in order to avoid those, you are advised to switch to Manjaro unstable branch
$ pamac search swift language
swift-mesonlsp 2.4.4-1 AUR
A language server for meson
swiftly-bin 0.1.0-1 AUR
A Swift toolchain installer and manager, written in Swift.
swift-language-git swift.DEVELOPMENT.SNAPSHOT.2023.09.02.a.r9.g550a0ce12-1 AUR
The Swift programming language, taken directly from the Apple
repository
swift-language 5.8.1-1 AUR
The Swift programming language and debugger
swift-bin-development 4:5.9.DEVELOPMENT-1 AUR
Binary builds of the Swift programming language (dev snapshot)
swift-bin 5.9-1 AUR
Binary builds of the Swift programming language