graphicsPort doesn’t return an Optional however currentContext does, so
cocoaCTX is an NSGraphicsContext? which is what the error message was trying to
tell you.
let cocoaCTX = NSGraphicsContext.currentContext()
let sysCTX = cocoaCTX?.graphicsPort as! CGContextRef?
is what you need to get an optional CGContextRef out of it (and it took me 3
shots to get that one right). ‘?’ after the cocoaCTX (which autocomplete adds
for you), a force downcast but to a CGContextRef? else you’ll go bang if the
NSGraphicsContext is nil
As Marco points out, that won’t work in your initializer, quite.
> On 2 Jul 2015, at 07:46, Rick Mann <rm...@latencyzero.com> wrote:
>
> I think I figured this out. graphicsPort does not return an Optional type. I
> guess the only way to know that is via Xcode's Code Completion, is that
> right? Oh, the docs seem to show it, too (assuming it can find either).
>
> Sorry for the noise.
>
>> On Jul 1, 2015, at 16:28 , Rick Mann <rm...@latencyzero.com> wrote:
>>
>> I'm trying to do this:
>>
>> class
>> Context
>> {
>> init()
>> throws
>> {
>> let cocoaCTX = NSGraphicsContext.currentContext()
>> guard let sysCTX = cocoaCTX.graphicsPort as! CGContextRef else { throw
>> Errors.InvalidContext }
>> CGContext = sysCTX;
>> }
>>
>> var CGContext : CGContextRef
>> }
>>
>>
>> But I'm getting
>>
>> error: value of optional type 'NSGraphicsContext?' not unwrapped; did you
>> mean to use '!' or '?'?
>> guard let sysCTX = cocoaCTX.graphicsPort as! CGContextRef else
>> { throw Errors.InvalidContext }
>> ^
>> !
>> In the typical if-let, you don't add the ?. If I do add the ?, I get:
>>
>> error: '_??' is not convertible to '_??'
>> guard let sysCTX = cocoaCTX.graphicsPort? as! CGContextRef
>> else { throw Errors.InvalidContext }
>> ~~~~~~~~~~~~~~~~~~~~~^
>>
>> Errors is an enum I created in a different file.
>>
>> I always seem to trip up on the conditional optional unwrapping. Not sure
>> what I'm doing wrong here. Help is much appreciated. Thanks!
>>
>> --
>> Rick Mann
>> rm...@latencyzero.com
>>
>>
>>
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>
>
> --
> Rick Mann
> rm...@latencyzero.com
>
>
>
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