<aura:component>

    <aura:attribute name="fieldApiNames" type="List" />
    <aura:attribute name="showSpinner" type="Boolean" default="true" />

    <aura:if isTrue="{!v.showSpinner}">
        <lightning:spinner alternativeText="Loading..." />
    </aura:if>

    <lightning:recordEditForm onload="{!c.handleLoad}" objectApiName="Account">
        <lightning:messages />

        <lightning:layout multipleRows="true">
            <aura:iteration items="{!v.fieldApiNames}" var="api">
                <lightning:layoutItem aura:id="formItems" size="6">
                    <div aura:id="top-div" />
                    <lightning:inputField aura:id="field" fieldName="{!api}" />
                    <div aura:id="bottom-div" />
                </lightning:layoutItem>
            </aura:iteration>
        </lightning:layout>
    </lightning:recordEditForm>

    <lightning:button title="Show Field Values" onclick="{!c.handleButton}" />

</aura:component>

({
    handleLoad : function(cmp, evt, helper) {
        cmp.set( "v.showSpinner", false );
    },

    handleButton : function(cmp, evt, helper) {
        var first = cmp.get("v.fieldApiNames")[0];
        cmp.find("formItems").forEach( function(item) {
            alert( item.find("field").get("v.value") );       <== ?
        } );
    }
})