Are utf-8 std::locales missing on iOS? - c++

Question

I'm trying to get std::locale that will be able to handle Russian symbols in my code.
std::optional< std::locale > TryGetLocale( const std::string& name )
{
try
{
std::locale res( name );
if( std::isalpha( L'ф', res ) )
return res;
else
return std::nullopt;
}
catch( ... )
{
return std::nullopt;
}
}
std::optional< std::locale > TryGenerateLocale( const std::string& name, const std::string base_name )
{
try
{
boost::locale::generator gen;
std::locale base( base_name );
auto res = std::locale( gen.generate( base, name ) );
if( std::isalpha( L'ф', res ) )
return res;
else
return std::nullopt;
}
catch( ... )
{
return std::nullopt;
}
}
std::locale TryGetLocale()
{
auto res = TryGetLocale( "ru_RU.utf8" );
if( !res )
res = TryGetLocale( "ru_RU.UTF-8" );
if( !res )
res = TryGenerateLocale( "ru_RU.UTF-8", "en_US.UTF-8" );
if( !res )
res = TryGenerateLocale( "ru_RU.UTF-8", "en_US.utf8" );
if( !res )
{
using namespace U_ICU_NAMESPACE;
int32_t count;
const Locale* list = Locale::getAvailableLocales( count );
for( size_t i = 0; i < static_cast< size_t >( count ); ++i )
{
res = TryGenerateLocale( "ru_RU.UTF-8", std::string( list[ i ].getName() ) + ".utf8" );
if( res )
break;
res = TryGenerateLocale( "ru_RU.UTF-8", std::string( list[ i ].getName() ) + ".UTF-8" );
if( res )
break;
}
}
if( !res )
{
std::terminate();
}
return *res;
}
On Android and desktops everything is ok. On iOS simulator everything is also ok, but when I try to launch this code on iOS device - I'm getting terminate, because I can't get any named std::locale. Is it normal behavior for iOS devices? Do they miss any UTF-8 c++ locales?