PSPDFAbstractFormAction

An optional array, specifying the form fields to include or exclude (based on the flags property) when executing this action.

Fields can be identified by their objectNumber (boxed as NSNumber) or their fullyQualifiedName. The array can hold a mix of both types!

From the PDF Reference, version 1.7:

(Optional) An array identifying which fields to reset or which to exclude from resetting, depending on the setting of the Include/Exclude flag in the Flags entry (see Table 239). Each element of the array shall be either an indirect reference to a field dictionary or (PDF 1.3) a text string representing the fully qualified name of a field. Elements of both kinds may be mixed in the same array. If this entry is omitted, the Include/Exclude flag shall be ignored; all fields in the document’s interactive form are reset.

@property (nonatomic, copy, readwrite, nullable)
    NSArray<id<PSPDFFormFieldIdentifier>> *fields;