Answer by trojanfoe for how to convert optional decimal type to String in swift

If you cast the conversion to Any, then that will work because the compiler is happy that either Decimal or String can used:

import Foundationlet iAmNil: Decimal? = nillet iAmDecimal: Decimal? = 12.34print(String(describing: (iAmDecimal ?? "") as Any))// Prints 12.34\n