I'm just going to throw this out there as a solution, not because I recommend
this approach (it's API misuse after all) but because it would work.
Instead of using an `NSString *` you could use a `SEL` (AKA `struct
objc_selector *`) since SELs are guaranteed to be unique for each given string
they represent (within a process; AFAIR).
So your code would become:
if (context == @selector(mediaLibraryLoaded))
{
// …
Or in Swift:
if context == Selector("mediaLibraryLoaded")
{
// …
(Swift's `Selector.init(_ str:String)` implementation
<https://github.com/apple/swift/blob/master/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift#L98>
just calls `sel_registerName` and (curiously) treats the returned pointer as a
C-string.)
Again, this is a blatant mis-use of the Objective-C API… but it is also a
built-in compiler-optimized guaranteed-interned string, it won't cause issues
when comparing to other arbitrary `void *`s, and the usage in Swift is almost
identical to Objective-C.
----
My 2¢: I'm still in favor of making all usages of `context` in your app
`NSObject *`s or `nil` because sometimes you do want to store an `NSDictionary
*` or other data in `context` that's meant to be read later. But if you're
stuck with using other libs that don't use `NSObject *`s or `nil`, or if you
really want to ensure your code won't crash because its making assumptions
about what's in the `context` your code registered, then I acknowledge your
case. Key point: I personally wouldn't use the `SEL` approach, but still.
— Slipp
> On Sep 24, 2016, at 12:34 AM, Graham Cox <graham....@bigpond.com> wrote:
>
>
>> On 24 Sep 2016, at 12:13 PM, Uli Kusterer <witness.of.teacht...@gmx.net>
>> wrote:
>>
>>> I expect the first thing -isEqualToString: does is a pointer comparison, so
>>> it’s unlikely to be significantly less performant for the case of when the
>>> pointers are literally identical.
>>
>> No, Graham, don't do that!
>>
>> There is no guarantee that the context is a valid object. It is just
>> supposed to be a unique pointer value so your class can tell a KVO
>> notification from notifications for other observers on the same object (e.g.
>> if a subclass observes the same value as a base class).
>
>
> Yep, I’ve realised (from this discussion) that that’s an invalid assumption
> of another kind.
>
> I’ve been revising code that does this as a result.
>
> Always something to learn :)
>
> —Graham
>
>
>
> _______________________________________________
>
> Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
>
> Please do not post admin requests or moderator comments to the list.
> Contact the moderators at cocoa-dev-admins(at)lists.apple.com
>
> Help/Unsubscribe/Update your Subscription:
> https://lists.apple.com/mailman/options/cocoa-dev/apple%2Bcocoa-dev%40slippyd.com
>
> This email sent to apple+cocoa-...@slippyd.com
_______________________________________________
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
