[SalesForce] How to Redirect Flow Users to a URL

You can do like this using lightning quick action

Updated code:

({
    doInit : function(component, event, helper) {
        var urlEvent = $A.get("e.force:navigateToURL");
        urlEvent.setParams({
          "url": someurl   
        });
        urlEvent.fire();
        setTimeout(function(){
           $A.get("e.force:closeQuickAction").fire();
        },500);

    }
})

But still this will not stop the show dialog

Dialog will open but after 500 millisecond t will disappear.

NOTE: URL hacks do not work in lightning experience.

Flow Type: Flow actions support only flows that include screens.

Input Variables Flow actions let you pass the value of the record's ID field into the flow, but that's it. If your flow has a Text input variable called recordId, the action passes the record's ID into that variable at runtime. If not, it doesn't and the flow tries to run anyway.

So the above is relevant only if your'e using screen flows Add a Flow As an Action on a Record

If you do need to use a flow without screens you can leverage lightning components(Embed a Flow in a Custom Lightning Component) to pass the recordId to the flow

<aura:component>
    <aura:handler name="init" value="{!this}" action="{!c.init}" />
    <lightning:flow aura:id="flowData" />
</aura:component>

Controller

({
    init : function (component) {
        // Find the component whose aura:id is "flowData"
        var flow = component.find("flowData");
        // In that component, start your flow. Reference the flow's Unique Name.
        flow.startFlow("myFlow");
    },
})

If you want to end up using in both classic and lighting use a custom button to Embed Flows in Visualforce Pages

<apex:page standardController="Opportunity" tabStyle="Opportunity" >
    <flow:interview name="ModemTroubleShooting">
        <apex:param name="oppId" value="{!Opportunity.Id}"/>
    </flow:interview>
</apex:page>