Thanks for that follow up, I’m still a little confused at why one direction
works and the other does not, but I’m getting there.
I’ve found another issue I’ll bug report, but it’s along the same lines and
wanted to run it by this thread. If I have an NSDecimalNumber, in Swift, and
perform math on a literal value, (product) the code compiles. If I assign that
value to a variable, or use any of the other Decimal/Double types, I cannot
compile. I would expect a Double to not work, but I would expect ‘Decimal’ to
work, in this case, as I’m not crossing the Objective C border. And, I’m
confused how using the literal ‘2.0’ is interpreted as an NSDecimalNumber, and
works in the ‘product’ stop, but I would expect the compiler to try and make it
into a Double, as it does on the ‘test’ variable.
let value = NSDecimalNumber(value: 2)
let test = 2.0 // double
let product = value.multiplying(by: 2.0) // compiles
let x = value.multiplying(by: Decimal(2.0)) // does not compile
let y = value.multiplying(by: Double(2.0)) // does not compile
let z = value.multiplying(by: test) // does not compile
Best,
Chris Anderson
> On Nov 11, 2016, at 6:07 PM, Philippe Hausler <[email protected]> wrote:
>
>
> NSDecimal is not toll free bridged, but it does have a bridge to
> NSDecimalNumber.
>
> So take this for example:
>
> @objc class Exam: NSObject {
> var grade: Double = 90.0
> }
>
> It would be reasonable to expect that is exposed in objc as:
>
> @interface Exam : NSObject
> @property double grade;
> @end
>
> and not:
>
> @interface Exam : NSObject
> @property NSNumber *grade;
> @end
>
> As it stands this is exposing as the structural type since that structural
> type comes from objective-c. Unlike String or Dictionary that have direct
> counterparts - NSDecimal and NSDecimalNumber both are sourced from the
> objective-c headers. That being said an API exposed in objc as returning a
> NSDecimalNumber should be exposed into swift as returning a Decimal (the
> struct NSDecimal). So if Exam was implemented in objc as such:
>
> @interface Exam : NSObject
> @property NSDecimalNumber *grade;
> @end
>
> that should be imported into swift as:
>
> class Exam : NSObject {
> var grade : Decimal
> }
>
>> On Nov 11, 2016, at 2:58 PM, Adam C. Lickel via swift-users
>> <[email protected] <mailto:[email protected]>> wrote:
>>
>> NSDecimal has toll-free bridging with NSDecimalNumber so you can still do as
>> casting when talking to an Objective-C API.
>>
>>> On Nov 11, 2016, at 2:56 PM, Chris Anderson via swift-users
>>> <[email protected] <mailto:[email protected]>> wrote:
>>>
>>> Sure thing. Yeah, ideally the bridging would be fixed, but at the least,
>>> correcting the documentation will be a good start. Will file, thanks.
>>>
>>> Best,
>>> Chris Anderson
>>>
>>>> On Nov 11, 2016, at 5:55 PM, Tony Parker <[email protected]
>>>> <mailto:[email protected]>> wrote:
>>>>
>>>> Hi Chris,
>>>>
>>>> Can you file a radar or JIRA for us on this? It looks like something
>>>> should be fixed in the documentation at least, or perhaps in the bridging.
>>>>
>>>> - Tony
>>>>
>>>>> On Nov 11, 2016, at 1:46 PM, Chris Anderson via swift-users
>>>>> <[email protected] <mailto:[email protected]>> wrote:
>>>>>
>>>>> I'm having problems with the type conversion between a Swift `Decimal`
>>>>> and an Objective C `NSDecimalNumber`.
>>>>>
>>>>> If I have the Swift class:
>>>>>
>>>>> @objc class Exam: NSObject {
>>>>> var grade: Decimal = 90.0
>>>>> }
>>>>>
>>>>> And try to use that Swift class in Objective C,
>>>>>
>>>>> Exam *exam = [[Exam alloc] init];
>>>>> NSDecimalNumber *result = [[NSDecimalNumber zero]
>>>>> decimalNumberByAdding:grade.value];
>>>>>
>>>>> I get the error:
>>>>>
>>>>> Sending 'NSDecimal' to parameter of incompatible type 'NSDecimalNumber *
>>>>> _Nonnull'
>>>>>
>>>>> as it seems like `grade` is being treated as an `NSDecimal` not an
>>>>> `NSDecimalNumber`. This seems incorrect as per
>>>>> https://developer.apple.com/reference/foundation/nsdecimalnumber
>>>>> <https://developer.apple.com/reference/foundation/nsdecimalnumber> it
>>>>> says
>>>>>
>>>>> "The Swift overlay to the Foundation framework provides the Decimal
>>>>> structure, which bridges to the NSDecimalNumber class. The Decimal value
>>>>> type offers the same functionality as the NSDecimalNumber reference type,
>>>>> and the two can be used interchangeably in Swift code that interacts with
>>>>> Objective-C APIs. This behavior is similar to how Swift bridges standard
>>>>> string, numeric, and collection types to their corresponding Foundation
>>>>> classes."
>>>>>
>>>>> So I'm not sure if 1) I'm doing something wrong. 2) there's an error in
>>>>> the documentation or 3) this is a Swift bug. Number 1 on that list is
>>>>> definitely the most likely, but I wanted to see what I’m missing here.
>>>>>
>>>>> I don't want to explicitly make the values in my Swift class
>>>>> `NSDecimalNumber` because then I cannot do simple arithmetic operations
>>>>> such as `+` without doing the whole ugly `decimalNumberByAdding` dance.
>>>>>
>>>>> Thanks for the help!
>>>>>
>>>>> Best,
>>>>> Chris Anderson
>>>>> _______________________________________________
>>>>> swift-users mailing list
>>>>> [email protected] <mailto:[email protected]>
>>>>> https://lists.swift.org/mailman/listinfo/swift-users
>>>>> <https://lists.swift.org/mailman/listinfo/swift-users>
>>>>
>>>
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