Hello, World

Most languages make you build a scaffold before you can print anything: a class, a main function, an entry-point declaration. Swift skips all of it. A .swift file's top-level code is the program — statements run top to bottom, in the order you wrote them.

print("Hello, World!")
print("Ship That Code")

//> Hello, World!
//> Ship That Code

Two statements, two lines. That is the entire program.

Why is there no main function?

There is one, technically — Swift generates it for you when a file contains top-level statements. The rule that matters: at most one file in a program may have top-level code. In a single-file exercise like this one that file is yours, so you never think about it. A real iOS app instead marks a type with @main and Swift calls into that. Same idea, different door.

What print actually does

print writes its arguments to standard output and then adds a newline. Both halves are adjustable.

The terminator: form is how you build one line out of several calls:

print("load", terminator: "")
print("ing...")

//> loading...

There is no line break between load and ing..., because the first call was told not to end its line.

Statically typed — but you rarely say a type out loud

Swift checks every type at compile time, so a whole family of mistakes never survives to runtime. It also infers almost all of those types from context, which means you write far fewer of them than in Java or C#.

let greeting = "Hello"
let year = 2026
print(greeting, year)

//> Hello 2026

You never wrote String or Int; the compiler worked both out from the literals. It will also reject greeting + year at compile time, before the program ever runs.

Getting the output exactly right

Automated tests compare your output character for character. Two near misses cost people a pass far more often than any real bug:

✗ Fails

print("Hello World")        // no comma
print("hello, world!")      // wrong capitals

✓ Passes

print("Hello, World!")

Punctuation, capital letters and spaces are all part of the answer.

Your exercise

Print exactly Hello, Swift! — comma after Hello, capital S, exclamation mark at the end. The starter is a single comment; add one print call under it.

The mistake the grader catches here is the near miss. This lesson's examples all print Hello, World!, and the reflex is to copy one of them — that fails, because the test wants Hello, Swift!. So do Hello Swift! with no comma and hello, swift! in lower case. The test compares the whole line, so the program can be perfectly correct Swift and still not pass.