View Mobile PSD Comps on my iPhone

Hi, hope someone can help with this. I'm designing some websites and have to create a mobile version as well (yes I know before you say it I should be using XD! But the client is asking for all work to be done in Photoshop). I'm currently using the app Skala, it's worked great in the past but lately it's been crashing constenly on me and not reliable anymore. I'm looking for a new app that can do the same thing but work better just like XDs mobile app. Any suggestions would be helpful. Thanks!