Phishing protection arrived on Gmail for Android a few months ago and now the same capabilities have been introduced to the iOS app. Over the coming weeks, the anti-phishing features will become available, reducing the chance of people being harmed by malicious links in emails.
Google will immediately block any links it considers malicious, though users have the option of proceeding if they want to risk it.
Going forward, when you click on a suspicious link in a Gmail message on your iPhone or iPad, we'll show the warning below. We recommend that you use caution before proceeding, because the link is likely unsafe. Only proceed if you're confident there's no risk. - Google