{"id":40125,"date":"2023-07-21T16:13:51","date_gmt":"2023-07-21T20:13:51","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=40125"},"modified":"2023-07-21T16:13:51","modified_gmt":"2023-07-21T20:13:51","slug":"a-fast-timestamp-parser-in-swift","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2023\/07\/21\/a-fast-timestamp-parser-in-swift\/","title":{"rendered":"A Fast Timestamp Parser in Swift"},"content":{"rendered":"

Juri Pakaste<\/a> (Mastodon<\/a>):<\/p>\n

It’s well known that DateFormatter<\/code>, the main timestamp formatter and parser Apple ships in Foundation, is not particularly fast. It’s flexible and it’s correct, but it takes its time. The newer ISO8601DateFormatter<\/code> has similar performance.<\/p>

[…]<\/p>

Swift’s C bridging is first-class; struct tm<\/code> and timegm(3)<\/code> are right there. After changing the code to use those, the whole String<\/code> to Date<\/code> conversion runs completely without heap allocations and it’s around 6–7 times faster than when doing the detour via DateComponents<\/code>.<\/p>

The final result, according to Benchmark<\/a>, is maybe around 15x the speed of the Foundation parsers. I’m pretty happy with it. It’s available as a Swift package<\/a>, there’s documentation<\/a>, and if you need something different or don’t feel like using a package, all the parsing code is in just one file you can copy over to your project.<\/p><\/blockquote>\n

You can set set it as a JSONDecoder.DateDecodingStrategy<\/code>.<\/p>\n\n

Previously:<\/p>\n