I want to write text in some custom fonts using keyboard Extension as these apps (1,2,3,4) are doing. I know how we can insert normal string in document proxy.
[self.textDocumentProxy insertText:mystring];
I have tried to insert NSAttributedString using above approach but I can't see any way to insert NSAttributedString to document proxy.
Some one can guide what will the best way to get rid of this issue? any suggestion will be appreciated.
It is not possible to insert attributed strings (or otherwise rich content) using the text document proxy.
The keyboards you have linked are not using custom fonts. They use (or abuse) Unicode symbols such as Enclosed Alphanumerics and Enclosed Alphanumeric Supplement.
In other instances, different alphabet symbols with visual similarity to latin symbols are used to create "funky" text, like here.
Last, some keyboard extensions, like the image keyboards, use the pasteboard to copy the rich content, and the user is responsible to paste it where he seems fit.
The apps you are referring to don't use NSAttributedString or custom fonts. They simply replace letters with similar-looking Unicode characters. You can see these characters in any OS X app inside Edit -> Special Characters menu.
来源：https://stackoverflow.com/questions/28940768/how-to-insert-nsattributedstring-using-custom-keyboard-extension