<ui:outputRichText value="{!v.code__c}" aura:id="code"
class="slds-rich-text-area__content"/>

copyText : function(component, event, helper) {
    helper.copyTextHelper(component, event, event.getSource().get("v.value"));
  }

copyTextHelper : function(component,event,text) {
    // Create an hidden input
    var hiddenInput = document.createElement("input");
    // passed text into the input
    hiddenInput.setAttribute("value", text);
    // Append the hiddenInput input to the body
    document.body.appendChild(hiddenInput);
    // select the content
    hiddenInput.select();
    // Execute the copy command
    document.execCommand("copy");
    // Remove the input from the body after copy text
    document.body.removeChild(hiddenInput);
    // store target button label value
    var orignalLabel = event.getSource().get("v.label");
    // change button icon after copy text
    event.getSource().set("v.iconName" , 'utility:check');
    // change button label with 'copied' after copy text
    event.getSource().set("v.label" , 'Copied');
  }