Swift 3 - Ambiguous use of < operator when comparing two dates

Question

When comparing two Dates in swift, I can compare using >, but not <. startTime, endTime and Date() are all of type Date (previously NSDate)

   //Broken Code
   if Date() >= startTime && Date() < endTime
   {
       ...
   }
   Gives ambiguous use of < operator error

  //Working Code
   if Date() >= startTime && endTime > Date()
   {
       ...
   }

Is there a specific reason this isn't working?

I actually found this example when trying to find the apple documentation, and they actually use this code http://www.globalnerdy.com/2016/08/29/how-to-work-with-dates-and-times-in-swift-3-part-3-date-arithmetic/

I started wondering if maybe it was the using of the && operator, or possibly just being an issue of the order, but even doing the code by itself as

if startTime < endTime {...}

But it returns the same order.

Obviously I have found the workaround, But I am very curious why this is happening.

@LeoDabus I should have put this in the code above, I actually did try that, acted like it wanted to work, and then after maybe 10-12 seconds the compiler came back and gave the same error. Another thing I tried was casting each specifically as a Date, I saw that elsewhere on SO. — Dallas, Sep 17 '16 at 01:00
I suspect you have extended NSDate to conform to comparable protocol, which it is not needed for Date (Swift 3) — Leo Dabus, Sep 17 '16 at 01:05
@LeoDabus I thought I commented that out! Thanks a ton, I am fixing all the errors from going to swift 3, and came across these before the error in the extension. — Dallas, Sep 17 '16 at 01:10
@LeoDabus feel free to put that as an answer, And ill accept it. — Dallas, Sep 17 '16 at 01:12

score 25 · Accepted Answer · answered Sep 17 '16 at 01:15

25

You have probably extended NSDate to conform to comparable protocol in Swift 2. Just remove it because Date now conforms to Comparable protocol in Swift3.

answered Sep 17 '16 at 01:15

Leo Dabus

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12

When some random dude from the Internet knows my code better than I do… – Ian Bytchek Jan 12 '17 at 22:15
1

The exact same scenario here: two Dates compared; < complains about being ambiguous, while > works. Indeed, NSDate was previously extended and made to adhere to Comparable (by whoever wrote the Swift2.x version of the app) and the < operator was overwritten. JUST the < operator :-) Leo Dabus, how on earth did you know ??? :-) – Florin Odagiu Feb 06 '17 at 13:04
1

It took me a while to figure out, but I had the following code from Swift 2 which I needed to REMOVE. static public func <(a: Date, b: Date) -> Bool { return a.compare(b) == ComparisonResult.orderedAscending } – Dale Clifford Mar 08 '18 at 22:48

Swift 3 - Ambiguous use of < operator when comparing two dates

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