:sparkles: Today I loaded a custom font in Compose/iOS :sparkles: It was not an easy experience, so ...

# compose-ios

[darkmoon_uk]

✨ Today I loaded a custom font in Compose/iOS ✨
It was not an easy experience, so hopefully this can save someone's sanity 🙃
I think there's a bug around the identity field...
Take the iOS function:

androidx.compose.ui.text.platform.Font(
    identity: String,
    data: ByteArray,
    weight: FontWeight = FontWeight.Normal,
    style: FontStyle = FontStyle.Normal
): Font

The identity field is documented as:
identity - Unique identity for a font. Used internally to distinguish fonts.
...which suggests it can be any arbitrary, unique string right?
Seemingly not. See in 🧵 👉 for more...

[darkmoon_uk]

I can't identify the pattern here so I'll just share my results:
• My first thought was to just use the Font filename for the identity - easy, right? Let's call the font InterStellar, so I had five variants to load:
◦ InterStellar-Regular
◦ InterStellar-Bold
◦ InterStellar-Light
◦ InterStellar-SemiBold
◦ InterStellar-Medium
• Using these above strings as identifiers causes a crash 💥; not at the point of loading the Font, but rather at the point of trying to render the font:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSMutableDictionary __addObject:forKey:]: object cannot be nil'

[darkmoon_uk]

Note at this point, I had no reason to believe the identifier was causing the issue; I thought this crash could be coming from anywhere in the Font rendering system... it was only after several hours of trial and error 😪 that I trimmed the FontFamily down to one font with the identifier test and... it rendered!

[darkmoon_uk]

Here's where it starts to get weird...
If I have two fonts with isa and isb as names, that crashes 💥

[darkmoon_uk]

If I have the same two fonts with test and tsst as names, it works ✅

[darkmoon_uk]

I thought that maybe, in addition to minimum length, maybe the dashes in the original names were rejected, so I filtered those out... still crash 💥

[darkmoon_uk]

Are uppercase letters a problem? I lower case it all so now we have e.g. interstellarbold , interstellarlight etc... nope, crash 💥

[darkmoon_uk]

Only around 4-6 characters seems to work, not to short, not too long ✅ alphabet yellow question

[darkmoon_uk]

I ended up implementing a static counter in my iOS loader so now I have font1 , font2, font3 etc. as internal identifiers.

[darkmoon_uk]

This works, but I don't know why 🤔

[darkmoon_uk]

@Dima Avdeev Maybe this will be of some use... ☝️

[Dima Avdeev]

Yeah, it's very interesting, Thanks!
Do you have public repo with this experiments?

[darkmoon_uk]

Not at present. I'll try to reproduce one, but that was enough for today 🙂

[cafonsomota]

how are you reading the font content to send it as data @darkmoon_uk? 👼