How can I find a font that contains a given character?

I have a font that I use for my app which only uses english characters. I use CoreText to display the text, and I notice that whenever someone enters a character that isn't included in the font (like an Arabic character), then the program hangs at this line:

CTFramesetterCreateFrame(textFramesetter, CFRangeMake(0, 0), textMutablePath, NULL); 

I have a couple of questions:

1. is it possible to know if a certain character is included in a font?
2. is it possible for the system to find a font that contains the unknown character?

Related: Check if certain character is supported by UIFont