Maybe your technical explanations are true (but not sure: my iPad, "given" by my employer, is not old and is up-to-date…), but what I can say is that on my iOS device, on Safari, the thin space is not displayed. Please stop arguing about the theory and take into consideration the reality…
And please stop to impose your thin space, as there is no consensus for it and while thin spaces are not displayed on iOS devices.
I'm definitely not alone to defend NNBSP in French. There are lot os sources, and your problem for having it invisible on your specific device does not cauyse any harm even to you.
Your display is not broken/unreadable even if your device uses ugly fonts with ugly/overlarge punctuations with extra padding (in fact it jsut happens that your font maps this NNBSP to zero-width, which is coherent with the design of its ugly punctuations)
Change your font preferences in your browser (instead of the legacy fonts), you'll see the difference if you want. But that's not needed at all for the UI that you'll want to make discrete and compact, to leave more space for the content. It would be a problem if you saw ugly boxes for unmapped glyphs, but your browser does not even do that!
Why do you want to force a visible space here ? When your device uses a font with builtin enlarged punctuations ? With such a font with ugly punctuations like ":", NNBSP being rendered invisible is NOT a problem. This is legit. But NBSP is definitely bad (even worse with your font, it would be definitely too large). You msut know that NNBSP is used in so many places. Apple has made statements about how to cope with that. If you use the default builting sans-serif fonts even in browsers, haing it invisible is correct; if you render the page with a serif font, the default builtin font "Times" correctly renders that NNBSP. In both cases, it is supported.
If you use other fonts than these defaults, you will see the difference if you insist,, but such use is only for page design or when writing text, and even in the Wikitext editor you can see it with the monospaced font. But for the UI rendering it's still best to have it rendered as zero-width near punctuations (not at all an accessibility problem for this font). In fact it better fits the limited screen size on lowend iPhones.
And on the web, nothing forbids you to change the fonts (there are preferences for that in Apple's web browser). Did you read the links above ? Apps and other browsers can still work around this when they need, even if fonts don't map this character and EVEN if they are forced by Apple to use the Safari's internal rendering engine.
You don't care, but you're part of a very small minority and the large majority want to use the standards and official recommendations (that don't even break your device and makes the content inacessible to you if you don't want to change the device settings).
A space not displayed is not a problem? Hum… Yes, it is a problem. In French typography, a space (thin is better, but not mandatory) is needed before punctuations like ":" or ";". So a space… must be displayed. Simple.
(most) People use their devices as they are, we don't have to expect they will change their fonts or use workarounds. We have to make sure spaces are displayed on all devices. Stop saying that only old devices don't display thin spaces: mine is not old (about 2 years) and is up-to-date.
You don't bring any proof that thin spaces are a standard (we don't use them at all on Wikipedia for example) and you ignore the fact that, even if it was a standard, it is not yet followed by all browsers/OS.
False. It must be added ONLY when punctuations in the fonts you use do not have enlarged paddings. It is not needed at all for monospaced fonts or if punctuations have been tuned to embed extra padding, as what is visible in the screenshots you provided above, which ios perfectly fine and shows NO bug at all.
And this is still not our problem: in French, spaces must be displayed before ";", ":", "!", etc., period. If iOS or other platforms don't display thin spaces, go talk to them, but don't use thin spaces as long as the result is that spaces are no displayed for readers. Please.
But the space IS present, I have never "removed" it. And it IS displayed (even in your image, it is visible with your iOS renderer, and accurately it is thin as expected).
So you've not demonstrated any actual problem. The French typography is respected even on your iOS device ! It is thin but clearly visible on the ouput (you can measure it easily,the gap on sides of the colon or question mark is about twice larger than the average gap between 2 letters).
You use bad faith argument by pretending you don't see it, when your screenshots clearly demonstrate the opposite.
Is this a joke?
You're the one using bad faith arguments by pretending seeing an imaginary space, when my screenshots clearly demonstrate the opposite.
Here's a comparison with the thin space (top) and without any space (bottom), can you now tell me where do you see a difference? (protip: there's none)
Actually, the majority (the general public, the readers) don't know what a non-breaking or narrow non-breaking space is, they just want a space before
: ; ! ? » and after
« like it's supposed to be in French, whatever their device or browser is. Period.
And they see that even in iOS (the screenshots show above demonstrate that the punctuations are not "too near" from the characters before or after them, there's alreadyu the thin space inside each punctuation sign. these are legacy fonts anyway from Apple, and if you want finer typography, Apple recommands application authors to use better fonts, or users to setup their browser.
NBSP is not suitable as it is really too large for normal reading (remember they won't have to edit these UI texts, they just want to read it and without wasting screen space. NBSP is wrong in all French texts for ALL users; it was only a workaround before the encoding in Unicode 3.0. And NNBSP is kept for all scripts, except for the Mongolian vertical script where it is deprecated and replaced by MVS, NNBSP remaining valid however for punctuations even in Mongolian; and Mongolian does not use spaces as group separators for numbers).
We talk here about French only, and your screenshot does not demonstrate any problem: the extra spacing is present and visible along with normal French punctuations (but the same punctuations are ugly in non-standard uses of punctuations like sequences "::" or ":-;". And there's no problem at all for terminal monospaced fonts where these spaces are not needed and can safely become zero-width (and still remain fixed width, non-justifiable, non-breaking and narrower than regular spaces or figure spaces in all cases).
No, there are no space at all.
Here's another screenshot.
Measure the gap between the two glyphs between the letter and the following "?", compare it to the gap with the previous letter; it is LARGER (yes, there's extra padding inside the "?" in that font, so that NNBSP does not need to be visible with that font).
This is Apple's design of that font. No bug ! Adding a NBSP will just make the resultint text more ugly and not compliant to common typographic practices. And it will behave very bad for UI design (remember we are translating an UI), or in Monospaced environment (where NNBSP is also zero-width), e.g. on terminals on old typewriters (where no extra spacing was needed at all).
In other devices (Linux, Windows...) NNBSP is what is needed to get the same spacing, because gaps are NOT part of the OpenType design of standard punctuations.
(I bet that this Apple font is ugly for Swedish, where a ":" can appear in the middle of a word to attach suffixes, and that ":" is not cutting the sentence in two parts but may be Apple provided a Swedish tuning in that font to conditionally cancel that extra gap between two letters). Apple has very specific proprietary rendering engine that an do that with complex AAT rules in its proprietary fonts, instead of standard OpenType fonts).
Anyway, AAT is being deprecated by Apple in favor of OpenType, but legacy fonts for MacOS and iOS will keep their AAT tables for legacy compatiblity reasons. The Apple's renderer in its browser allow applications to drop the AAT rules and use only OpenType/TrueType rules (and in that case NNBSP will be distinctly displayed, and no gap will be added into OpenType/TrueType metrics, NNBSP will be non-zero width). These Apple tricks in its default legacy fonts are not used in Times (recommanded for text publishing, and also used normally by default on the web; Apple also offers other fonts now for web content and applications UI, where NNBSP is mapped or handled directly by the renderer without needing any extra mapping).
Did you try changing your default font instead of the proprietary legacy ones (that have also poor I18n support with limited coverage for Latin) ?