IOS is more secure largely because of its closed-source nature, strict app review process, and timely OS updates. Apple controls every aspect of its ecosystem. Android, being open-source, is more vulnerable to security threats, although recent Google security improvements have closed some gaps. https://www.diigo.com/item/note/axyb1/ng3e?k=7dfb0a9607521b21ef0f258bfed51ef0