[swift-users] Foundation on Linux `CFBooleanGetTypeID`/`CFGetTypeID`

Tony Parker anthony.parker at apple.com
Tue May 24 15:07:10 CDT 2016

Let’s get a bug into JIRA, then we’ll figure out what we should do here.

- Tony

> On May 24, 2016, at 1:03 PM, Jens Alfke <jens at mooseyard.com> wrote:
>> On May 24, 2016, at 12:52 PM, Tony Parker <anthony.parker at apple.com <mailto:anthony.parker at apple.com>> wrote:
>> One other possibility is using the objCType property on NSNumber’s superclass NSValue to check.
> That doesn’t work, unfortunately, at least not with Apple’s Foundation. NSNumbers initialized with booleans have objcType “c” because `BOOL` is just a typedef for `char`. So the only way to tell a boolean apart from an 8-bit int is to compare the object pointer against the singleton true and false objects.
> Here’s a snippet of Obj-C code I use for this in my JSON encoder:
>     char ctype = self.objCType[0];
>     switch (ctype) {
>         case 'c': {
>             // The only way to tell whether an NSNumber with 'char' type is a boolean is to
>             // compare it against the singleton kCFBoolean objects:
>             if (self == (id)kCFBooleanTrue)
>                 return yajl_gen_bool(gen, true);
>             else if (self == (id)kCFBooleanFalse)
>                 return yajl_gen_bool(gen, false);
>             else
>                 return yajl_gen_integer(gen, self.longLongValue);
>         }
>> I haven’t seen how much of this is implemented in corelibs-foundation yet. 
> I took a peek at the Swift NSNumber and NSValue implementations on Github, and the objcType stuff doesn’t seem to be functional. It looks like objcType will only have a value if the object was initialized as an NSValue with the type code passed in, not if the typical NSNumber initializers were used.
> —Jens

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