Ionic v3 and braintree Integration (IOS)

Hi guys.

Is anybody here tried using integrating braintree dropin?

Everything works fine in Android but not in IOS. Please have a look with my code below:

this.http.setDataSerializer('json');
      this.http.post('GET_BRAINTREE_TOKEN_URL', {customer_id: customer_id}, headers).then((response) => {
        braintree.dropin.create({
          authorization: response.data,
          container: '#dropin-container'
        }, (createErr, instance) => {
          button.addEventListener('click', () => {
            instance.requestPaymentMethod((err, payload) => {
                this.http.post('BRAINTREE_CHECKOUT_URL', {
                payment_method_nonce: payload.nonce
              }, headers).then((resp) => {

              });
            });
          });
        });
      });

This braintree loading will show in IOS but not the dropin UI. It will automatically remove the loading UI and then nothing happens.

Can anyone of you here help me please? Thanks