如何解决EXC_BAD_INSTRUCTION（代码= EXC_I386_INVOP，子代码= 0x0）

Question

每当我尝试使用数据库连接到我的应用时，都会弹出此错误

while { (rsMain!.next()) {
        let productName = rsMain?.string(forColumn: "name")
        let keywords = rsMain?.string(forColumn: "keywordtext")
        let multiField = MultiField(aField1: productName! as NSString, aField2: keywords! as NSString)
        self.dataArray.append(multiField)
        }
    }