Q:

Get a list of API Names of all Fields for an Object.

Is it possible to get a list of all API Names for all fields on an object?
Schema.DescribeSObjectResult r =Object__c.sObjectType.getDescribe();
List<String>apiNames =  new list<String>();
for(Schema.DescribeSObjectResult result : r){
   apiNames.add();   //this is where I am lost. 
}

A:

You can use the fields method to get the Schema.SObjectTypeFields.
Schema.DescribeSObjectResult r = Account.sObjectType.getDescribe();
List<String>apiNames =  new list<String>();
for(string apiName : r.fields.getMap().keySet()){
   apiNames.add(apiName);
}
System.debug(apiNames);

