Embedded Iframe content is not loading in IOS devices – safari

I have iframe content loading external source. my code is like this

<iframe title="xyz" allowtransparency = "true" marginheight="0"
  marginwidth ="0" class="investisIframe"
  src="https://irs.tools.investis.com/Clients/uk/bt/SharePriceLookup/Default.html?culture=en-GB"
  frameborder="0" id="001" width="100%" height="500">
</iframe>

Above code works fine in android and windows devices. But not working in ios devices. Please help me to resolve this issue

1. I have tried clearing the cache still the same issue.
2. By adding timestamp at the end of url then also same issue.