How to create dependent picklist in salesforce lightning component?

Question

I Have written following code Component --

<aura:handler name="init" value="{!this}" action="{!c.doInit}"/> 
<aura:attribute name="country" type="Lead"/>
<ui:inputSelect label="Country" class="dynamic" aura:id="InputSelectDynamic" value="{!v.leadObj.Country__c}" change="{!c.onSelectChange}"/> 
<aura:if isTrue="{!v.InputSelectDynamic != '--None--'}" >
    <ui:inputSelect label="States" class="dynamic" aura:id="states" value="{!v.leadObj.States__c}" /> 
</aura:if>

Java Script Controller -

({
    doInit : function(component, event, helper) {
        var action = component.get("c.getLeadCountry");
        var inputsel = component.find("InputSelectDynamic");
        var opts=[];
        action.setCallback(this, function(a) {
            for(var i=0;i< a.getReturnValue().length;i++){
                opts.push({"class": "optionClass", label: a.getReturnValue()[i], value: a.getReturnValue()[i]});
            }
            inputsel.set("v.options", opts);

        });
        $A.enqueueAction(action);
    },
    onSelectChange : function(component,event,helper){
        var action = component.get("c.getLeadState")
        var inputsel = component.find("states");
        var opts=[];
        action.setCallback(this, function(a) {
            for(var i=0;i< a.getReturnValue().length;i++){
                opts.push({"class": "optionClass", label: a.getReturnValue()[i], value: a.getReturnValue()[i]});
            }
            inputsel.set("v.options", opts);

        });
        $A.enqueueAction(action);
    }
})

Apex Controller -

public class DependentPicklistDemoController {
    @AuraEnabled
    public static List<String> getLeadCountry(){
        List<String> options = new List<String>();
        options.add('--None--');
        Schema.DescribeFieldResult fieldResult = lead.Country__c.getDescribe();
        List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
        for (Schema.PicklistEntry f: ple) {
            options.add(f.getLabel());
        }
        return options;
    }
    @AuraEnabled
    public static List<String> getLeadState(){
        List<String> options = new List<String>();
        Schema.DescribeFieldResult fieldResult = lead.States__c.getDescribe();
        List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
        for (Schema.PicklistEntry f: ple) {
            options.add(f.getLabel());
        }
        return options;
    }
}

I am not able to filter child picklist value on the basis of parent picklist values. Please help--