iPhone Device token not getting pushed to salesforce through SalesforceMobileSDK for CORDOVA

Question

I am trying to implement Apple Push Notification through SalesforceMobileSDK for a Hybrid mobile app (IONIC, Cordova).

The problem is that the device token is not getting registered to Salesforce user. When I use the below-mentioned code suggested in the salesforce docs-

cordova.require("com.salesforce.util.push").registerPushNotificationHandler( function(message) {
        // add code to handle notifications
    },
    function(error) {
        // add code to handle errors
} );