Lightning Component Template - This can be used as a boiler plate code for lightning component.

Example.cmp

<aura:component implements="flexipage:availableForRecordHome,force:hasRecordId,flexipage:availableForAllPageTypes" 
				controller="<CONTROLLER_NAME>" access="global">
	
	<aura:attribute name="recordId" type="Id" />
	<aura:attribute name="showSpinner" type="Boolean" default="false" />

	<aura:handler name="init" action="{!c.doInit}" value="{!this}"/>

	<!-- Spinner component -->
	<aura:if isTrue="{!v.showSpinner}">
		<lightning:spinner variant="brand" size="large" aura:id="mySpinner"/>
	</aura:if>
	
</aura:component>

ExampleController.js

({
	doInit : function(component, event, helper) {
		// Create the action
		var action = component.get("c.<CONTROLLER_METHOD_NAME>");
		action.setParams({
		    caseId : component.get("v.<PUT_PARAM_NAME>")
		});
		component.set("v.showSpinner","true");
		// Add callback behavior for when response is received
		action.setCallback(this, function(response) {
		    component.set("v.showSpinner","false");
		    var state = response.getState();  
		    var toastEvent = $A.get("e.force:showToast");
		    if (component.isValid() && state === "SUCCESS" ) {
				var result = response.getReturnValue();
				//<LOGIC_GOES_HERE>
				toastEvent.setParams({
					"title": "Success!",
					"type": "success",
					"message": "<SUCCESS_MESSAGE_GOES_HERE>"
				});
							
		    }
		    else {
			console.log("Failed with state: " + state);
			toastEvent.setParams({
			  "title": "Error!",
			    "type": "error",
			    "message": "Error "+response.getError()[0].message
			});
		    }
		    toastEvent.fire();
		});
		// Send action off to be executed
		$A.enqueueAction(action);
	}
	
})