There's actually a system-level thing, where password manager apps can register an extension to provide password form-filling, and then apps just include a butt

There's actually a system-level thing, where password manager apps can register an extension to provide password form-filling, and then apps just include a button (generally a keyhole one) which you tap to trigger the relevant extension sheet from which you can choose your password app. Here's the first screenshot of the flow I found: https://releasenotes.docs.salesforce.com/en-us/winter17/release-notes/rn_mobile_s1_newfeat_password.htm https://releasenotes.docs.salesforce.com/en-us/winter17/rele... iOS11 added a new variant on this, with a little key icon in the keyboard when you're in a password area, but it's only filling from the system keychain and isn't open to third parties. (Yet?) See: https://techcrunch.com/2017/06/08/ios-11s-new-password-autofill-for-apps-wont-work-with-or-replace-your-favorite-password-manager/ https://techcrunch.com/2017/06/08/ios-11s-new-password-autof...