Got some clarity on this from Apple folks on Twitter: https://twitter.com/jtbandes/status/830159670559993856
On Fri, Feb 10, 2017 at 12:54 PM, Michel Fortin <michel.for...@michelf.ca> wrote: > I did file one (30314719). I might not have explained the problem clearly > enough, I suppose, because at the time I was misinterpreting the API > contract thinking it was the new AppKit Touch Bar stuff that was violating > it instead. That bug now sits closed and I hesitate opening a new bug for > the same problem just to ask it to be fixed in another way. Meanwhile I > found an acceptable workaround that I attached to the existing bug report > in addition and I posted all this to the list. Hopefully someone at the > right place will notice. > > But yeah... maybe I should file another bug, against Foundation's Swift > interface this time, since NSTextStorage's string property comes from > NSAttributedString. I'll think about it. > > > Le 10 févr. 2017 à 11:36, Jacob Bandes-Storch <jtban...@gmail.com> a > écrit : > > This seems like a bug (missing feature?) in how the API is imported for > Swift. You might consider filing a Radar. > > On Thu, Feb 9, 2017 at 3:12 PM Michel Fortin via swift-users < > swift-users@swift.org> wrote: > >> The `string` property of `NSTextStorage` is of type `String`, but the >> contract it must implement is that it should return the backing store of >> the attributed string (the underlying `NSMutableString` used as the backing >> store). It seems to me that this makes it impossible to implement correctly >> a subclass of `NSTextStorage` in Swift, because Swift automatically wraps >> the `NSString` into a `String` and the underlying mutable storage is not >> passed around. >> >> Here's the documentation for that method: >> https://developer.apple.com/reference/foundation/ >> nsattributedstring/1412616-string >> >> In case the contract isn't clear from the documentation (it wasn't for >> me), I got a confirmation as a response in radar 30314719: >> > It’s returning a copy of the backing store, but the contract is >> actually returning the backing store string. The copy storage declaration >> in the property spec is only used for setter implementation. >> >> So looks like this is impossible to model correctly in Swift due to the >> automatic bridging to `String`. Some APIs in AppKit expect the `NSString` >> they receive to mutate when mutating the text storage (touch bar >> suggestions in `NSTextView`) and will do bad things this isn't the case. >> >> Obviously, I can work around this by writing some Objective-C code, but >> it'd be better if I could avoid splitting the class implementation between >> two languages. There's another way using swizzling to map the Objective-C >> method to a Swift implementation of the same method that has the correct >> signature, and that's probably what I'll end up doing unless a better >> solution can be pointed out to me. >> >> >> -- >> Michel Fortin >> https://michelf.ca >> >> _______________________________________________ >> swift-users mailing list >> swift-users@swift.org >> https://lists.swift.org/mailman/listinfo/swift-users >> > > -- > Michel Fortin > https://michelf.ca > >
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