Salesforce Apex provides developers with the ability to retrieve ISO Code information for specific countries. This is useful for international applications where a user’s country or language needs to be stored. To prevent confusion, ISO Codes are often used in such cases.

There are several ways to create an Apex method to retrieve an ISO Code. Let’s see one of them.

If you want to get the ISO code by country name, see this post

public static String getIsoCodeByCountryName(String countryName) {
    if (countryName == null) return null;
    Schema.DescribeFieldResult fieldResult = User.Countrycode.getDescribe();
    List<Schema.PicklistEntry> pickListValues = fieldResult.getPicklistValues();
    for (Schema.PicklistEntry pickListEntry : pickListValues) {
        // pickListEntry.getLabel() returns the country name
        // pickListEntry.getValue() returns the country code
        if (pickListEntry.getLabel().toLowerCase() == countryName.toLowerCase()) {
            return pickListEntry.getValue();
        }
    }
    return null;
}

How to test the Apex method getIsoCodeByCountryName

@isTest static void testGetIsoCodeByCountryNameDynamic() {
    // given
    List<String> countries = getCountries();
    for(String country :countries){
    // when
        String isoCode = getIsoCodeByCountryName(country);    
     // then
        System.assert(isoCode != null);
    }
}
    
@isTest static void testGetIsoCodeByCountryNameInvalid() {
    // given
    String country = 'invalid country';
    // when
    String isoCode = getIsoCodeByCountryName(country); 
    // then
    System.assert(isoCode == null);
}
    
@isTest static void testGetIsoCodeByCountryNameNull() {
    // given
    String country = null;
    // when
    String isoCode = getIsoCodeByCountryName(country); 
    // then
    System.assert(isoCode == null);
}

See that one of our test cases uses one aux method called getCountries to get all the countries available in the your Salesforce instance

public static List<String> getCountries(){
    Schema.sObjectType objType = Contact.getSObjectType();
    Schema.DescribeSObjectResult objDescribe = objType.getDescribe();
    map<String, Schema.SObjectField> fieldMap = objDescribe.fields.getMap();
    list<Schema.PicklistEntry> values = fieldMap.get('MailingCountryCode').getDescribe().getPickListValues();
    List<String> countries = new List<String>();
    for (Schema.PicklistEntry v : values){
        countries.add(v.getLabel());
    }
    return countries;
}