Hi, 
 
 In below code popup alert is displayed in home page for first time only when user login 

 Below code is working perfect in lightning in salesforce I want to make it work in mobile app as well please suggest me how to implement this feature. 


  Aura Component:

<aura:component 
               implements="flexipage:availableForAllPageTypes"
                access="global">
    <aura:handler name='init' action="{!c.init}" value="{!this}" />
    <aura:attribute name="isOpen" type="boolean" default="false" />
    <div class="slds-backdrop" aura:id="Modalbackdrop"></div>
    <aura:if isTrue="{!v.isOpen}">
        <div role="dialog" tabindex="-1" aria-labelledby="header43" class='pop-up slds-modal' aura:id="popupDiv1">
            <div class="slds-modal__container">
                <div class="slds-modal__pinner">
                    <div class="message">
                        <p>You logged into salesforce Lightning </p>                    
                    </div>
                    <div class="slds-form-element">
                        <lightning:button variant="success" label="Ok" title="ok" onclick="{! c.close }" />
                        
                    </div>
                </div>
            </div>
        </div>
    </aura:if>
</aura:component>

JS Controller:

({
    init : function(component, event, helper) {
        var temperorySession = localStorage.getItem('tempSession');
        if(temperorySession == '1')
        {  
            component.set("v.isOpen", false);
        }
        else
        {
            component.set("v.isOpen", true);
            var cmpTarget1 = component.find('popupDiv1');
            var cmpBack1 = component.find('Modalbackdrop1');
            $A.util.addClass(cmpTarget1, 'slds-fade-in-open');
            $A.util.addClass(cmpBack1, 'slds-backdrop--open');
        }
        localStorage.setItem('tempSession', '1');
        
    },
    close: function(component, event, helper) {
        component.set("v.isOpen", false);
    }
})

STYLE:

.THIS.pop-up {
    display: block;
    opacity: 1;
    visibility: visible;
}

.THIS .slds-modal__inner {
    background: yellow;
    padding: 20px;
    text-align:left;
}

.THIS .slds-modal__pinner {
    background: #fff;
    padding: 20px;
}