I use fontstash to draw a str = @"i:ə:ɔ:u:ɑ:i:ɜ:ɔ:u:ɑ:iɜɔuɑ", the glyph of "ɜ" display wrong. use "PingFangSC-Regular"  use "SFUIText-Light"  use "HelveticaNeue"  addtional, I suggest updating stb_trunetype to the latest version in order to support OpenType format, which internal use of the CCF table.