dominicegginton / nanoseconds Goto Github PK

There don't seem to be unit tests that check that the subtraction values are reasonable. I had my own tests in my app, and sleeping for two seconds doesn't yield a difference greater than one second.

let before = Now()
sleep(2)
let after = Now()
XCTAssertGreaterThan((after - before).seconds, 1)
// XCTAssertGreaterThan failed: ("0.048024575") is not greater than ("1.0")

Unless I'm reading the the code for this project wrong it suggests you have a fundamental misunderstanding of the TimeInterval type in Swift.

TimeInterval is measured in seconds. So if you wanted to initialise a TimeInterval as a specific number of seconds you would initialise it directly, eg:

var seconds: TimeInterval = 10 // 10 seconds.

Your code instead has this:

public init (seconds: Double) { self = seconds * 1e+9 }

Which multiplies the stored TimeInterval by 1_000_000_000. Making the value stored be some multiple of a billion seconds. If you then passed this value to any Swift API expecting a TimeInterval you would be waiting a very long time.

I recommend you re-evaluate your assumptions here. Or better yet adopt the new iOS 16 Clock APIs.

If your intention was to create a Nanosecond type this logic would make sense. But you shouldn't use a Double (aka TimeInterval) for that. Instead look at Int64.