SOLVED: BetterRest confusion as binary operator used with two different types without conversion

@BytesizeLearning

Feb '23

So I have just finished the second episode on day 27 for the BetterRest app and in it Paul subtracts a Double from a Date.

How is this possible? as you can't subtract an Int from a Double because they're two different types.

So how are you able to subtract a Double from a Date?

@Greenamberred HWS+

Feb '23

As Paul says in the video and the notes, Apple have provided the API. This means that they have defined the operation of subtracting a TimeInterval (which is a Double) directly from a Date.

If you open the Quick Help in Xcode ( ⌥ + ⌘+ 3 )and search for Date, you will see that there is a static func - defined for Date and TimeInterval.

@BytesizeLearning

Feb '23

Thanks. It was just confusing that you can't mix types. It still doesn't make sense two different types being used with the operator but now I know it's possible and TimeInterval is just a typealias for Double

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