Thanks Roland.
On 17 Oct 2014, at 00:20, Roland King <r...@rols.org> wrote:
>
>> On 17 Oct 2014, at 6:13 am, Kevin Meaney <k...@yvs.eu.com> wrote:
>>
>> Hi,
>>
>> I'm beginning to feel this above my pay grade as I can't seem to work it out.
>>
>> I have a framework in Objective-C. I've been writing some tests for it, and
>> to make life fun I've been writing the tests in Swift.
>>
>> I have a property of a class in the objective-c framework declared like so:
>>
>> @property (nonatomic, copy) CGImageRef (^createImage)(NSDictionary *);
>>
>> In my tests I'm trying to write a function that I can assign to the property.
>>
>> In the most basic form the function looks like this, I'm ignoring the passed
>> in dictionary for the purposes of asking this question:
>>
>> func createCGImage2(dictionary: [NSObject:AnyObject]) -> CGImage {
>> let jpegURL = NSBundle.mainBundle().URLForResource("myimage",
>> withExtension:"jpg")
>> let imageSource = CGImageSourceCreateWithURL(jpegURL, nil)!
>> let theImage = CGImageSourceCreateImageAtIndex(imageSource, 0, nil)
>> return theImage
>> }
>>
>> When I try to set the property with the function I get:
>>
>> error: cannot convert the expression's type '([NSObject : AnyObject]) ->
>> Unmanaged<CGImage>!' to type '(([NSObject : AnyObject]!) ->
>> Unmanaged<CGImage>!)!?'
>>
>> Now, if I have a function declared like so:
>>
>> func createCGImageFromDictionary(dictionary: [NSObject:AnyObject]!) ->
>> Unmanaged<CGImage>!
>>
>> error: cannot convert the expression's type '([NSObject : AnyObject]!) ->
>> Unmanaged<CGImage>!' to type '(([NSObject : AnyObject]!) ->
>> Unmanaged<CGImage>!)!?'
>>
>> I'm still a long way off. There's an extra () in there and an extra !? at
>> the end that I really don't know how to interpret. Also I don't know how to
>> convert the result of CGImageSourceCreateImageAtIndex to a
>> Unmanaged<CGImage> as a return value.
>>
>> I've been through various bits of the documentation, but something isn't
>> clicking so that I understand how this stuff works so that I can try and
>> solve it.
>>
>> Kevin
>>
>> __
>
> ok this simple test works for me .. I also don’t understand the extra parens
> etc in your example. So where does your code differ from the below? Note I
> set it both with a public function and a closure, just to see if it works.
A detail I should have included. The @property is declared in the optional
section of a protocol. I know the object in question has implemented the
property. But that explains the extra requirements for unwrapping.
I've put together a gist where I've attempted to play with this.
https://gist.github.com/SheffieldKevin/a06907e163885f249548
I got the assigning to a property working when that property was declared as
part of the class, but not when it has been declared in the optional section of
a protocol. So I was able to duplicate what you did Roland. But no matter what
I try, documentation I read I can't make it work when the property is declared
in the protocol.
I got myself distracted because the project I setup to try out stuff was an
objective-c command line tool and I also had trouble calling swift code from
Objective-c. I could not get a swift function that wasn't a class or instance
method to be callable from Objective-c.
Kevin
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