Does Swift support number suffixes?

No.

The ‘correct’ way to do this is to write something like 42 as UInt64. The most common way that folks actually write this is with UInt64(42). Since SE-0213 these have been mostly equivalent.

Having said that, most of the time you don’t need to do this. If you find yourself doing it a lot, post an example here and we can see if there’s a better way.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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Actually I don't have 'a lot' examples. I just started real app development using Swift a couple of months ago.

For this specific scenario, I really like to have what I have in C/C++.

Advantages:

1. It can save a few key strokes and makes me as a developer feel better; and even more, makes Swift feels more swift.

auto n = 12345ull;

vs

var n: UInt64 = 12345

1. Real world example (unit test):

func testByteSize() {
        let tests = [
            (s: "1234", v: 1234),
            (s: "1kb", v: 1024),
            (s: "1234k", v: 1234 * 1024),
            (s: "3mb", v: 3 * 1024 * 1024),
            (s: "2GB", v: 2 * 1024 * 1024 * 1024),
            (s: "7tb", v: 7 * 1024 * 1024 * 1024 * 1024),
        ]

        for test in tests {
            let n = test.s.parseByteSize()
            XCTAssertNotNil(n)
            XCTAssertEqual(UInt64(test.v), n!)
        }
    }

If Swift allows me to code a number as 1234ull, I won't have to do the UInt64(test.v) cast. Moreover, I really like the tuple's v field be UInt64 instead of default Int.

auto n = 12345ull;

Well, n is unsigned long long, which isn’t necessarily uint64_t in C-based languages (-:

Real world example (unit test)

That’s a bit tricky because you rely on the tuple labels. I’d probably give the array a type:

let tests: [(s: _, v: UInt64)] = [
    ("1234",  1234),
    ("1kb",   1024),
    ("1234k", 1234 * 1024),
    ("3mb",   3 * 1024 * 1024),
    ("2GB",   2 * 1024 * 1024 * 1024),
    ("7tb",   7 * 1024 * 1024 * 1024 * 1024),
]

Note that I’m using _ as a type placeholder for s (per SE-0315). I’m also relying on Swift’s built-in conversion from unlabelled to labelled tuples. This yields a value with the right type with a reasonably small amount of ceremony.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"