Layout, products & build/test/run

let manifest = """
// Package.swift (illustrative)
import PackageDescription
let package = Package(
  name: "MyPkg",
  products: [
    .library(name: "MyLib", targets: ["MyLib"]),
    .executable(name: "MyApp", targets: ["MyApp"])
  ],
  targets: [
    .target(name: "MyLib"),
    .executableTarget(name: "MyApp", dependencies: ["MyLib"]),
    .testTarget(name: "MyLibTests", dependencies: ["MyLib"])
  ]
)
"""
print(manifest)

// Library code (Sources/MyLib/MyLib.swift)
public struct Greeter {
    public init() {}
    public func hello(_ name: String) -> String { "Hello, \\(name)" }
}

// Executable entry (Sources/MyApp/main.swift)
let g = Greeter()
print(g.hello("World"))

let cmds = """
# Build (debug by default)
swift build

# Run an executable product
swift run MyApp

# Execute tests (XCTest)
swift test

# Release build (optimized)
swift build -c release
"""
print(cmds)

let notes = """
Artifacts live under .build/:
  • debug/ and release/ contain compiled products
  • x86_64-apple-macosx / arm64-apple-* vary by platform/arch
Tips:
  • Keep one target per responsibility
  • Name products simply; match target folders
  • Put tests in Tests/<TargetName>Tests
"""
print(notes)