[swift-evolution] Thoughts on "Fully eliminate implicit bridging conversions from Swift"

[simon gladman]

Hi,

The error is get is "*Contextual type 'AnyObject' cannot be used with
dictionary literal*" - and I get the same issue with your approach.

With the CGFloat, I get "*Value of type 'CGFloat' does not conform to
expected dictionary value type 'AnyObject'*'".

Simon



Simon Gladman     +44 7973 669691

Blog: http://flexmonkey.blogspot.co.uk
GitHub: https://github.com/FlexMonkey
Twitter: @FlexMonkey <https://twitter.com/FlexMonkey>


On 24 May 2016 at 17:18, Charlie Monroe <charlie at charliemonroe.net> wrote:

> What error do you get (i.e. why doesn't it compile)?
>
> Have you tried this?
>
> let result: [String : AnyObject] = [
> "inputImage": [
> kCIAttributeIdentity: 0,
> kCIAttributeClass: "CIImage",
> kCIAttributeDisplayName: "Image",
> kCIAttributeType: kCIAttributeTypeScalar
> ]
> ]
> return result
>
> Charlie
>
> On May 24, 2016, at 6:07 PM, simon gladman via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> Apologies for arriving a little late to the party and I hope this is a
> suitable forum to discuss this subject. I've spent some time over the last
> few days moving a large Core Image project to Swift 3.0 and come across
> some side effects which I think are related to proposal SE-0072, *Fully
> eliminate implicit bridging conversions from Swift*.
>
> First off, rightly or wrongly, I've always typed the scalar parameters of
> my subclassed *CIFilters* as *CGFloat*. It makes working with *CIVectors*
> and *CGRects* cleaner and feels more "Swifty" than using *NSNumber*.
> However, moving to Swift 3.0, using anything apart from an *NSNumber*
> breaks. For example:
>
>         let radius: CGFloat = 25
>
>
>         let blur = CIFilter(
>             name: "CIGaussianBlur",
>             withInputParameters: [kCIInputRadiusKey: radius])
>
> The same with passing arguments to a *CIKernel*, *CIWarpKernel* or
> *CIColorKernel*:
>
>         kernel.apply(
>             withExtent: CGRect(x: 0, y: 0, width: 100, height: 100),
>             arguments: [radius])
>
> Secondly, the attributes property of a filter (of type *[String:
> AnyObject]*) which I'd normally code along the lines of:
>
>     override var attributes: [String : AnyObject]
>     {
>         return [
>             "inputImage": [
>                  kCIAttributeIdentity: 0,
>                  kCIAttributeClass: "CIImage",
>                  kCIAttributeDisplayName: "Image",
>                  kCIAttributeType: kCIAttributeTypeScalar]
>         ]
>     }
>
> ...fails to compile. kCIAttributeTypeScalar is of type *String* and needs
> to be cast to *NSString* and the dictionary itself needs to be cast to
> *AnyObject*:
>
>     override var attributes: [String : AnyObject]
>     {
>         return [
>             "inputImage": [
>                  kCIAttributeIdentity: 0,
>                  kCIAttributeClass: "CIImage",
>                  kCIAttributeDisplayName: "Image",
>                  kCIAttributeType: kCIAttributeTypeScalar as NSString] as
> AnyObject
>         ]
>     }
>
> It seems awkward to me that the constant supplied by Core Image to
> describe an attribute's type needs to be cast to another type to get it
> working.
>
> Are these changes just something that we'll need to live with? Are they
> still in flux? Have I totally misunderstood everything and there's a more
> elegant solution?
>
> Any thoughts would be greatly appreciated!
>
> Simon
>
>
> Simon Gladman     +44 7973 669691
>
> Blog: http://flexmonkey.blogspot.co.uk
> GitHub: https://github.com/FlexMonkey
> Twitter: @FlexMonkey <https://twitter.com/FlexMonkey>
>
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>
>
>
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