With iOS 9 Apple has given some serious love to its Notes app, including many features that you often have to purchase an app to get - drawing, some rich text editing features like bold, italics, etc, and capabilities like making different types of lists (in particular I like the checklist option - great for making shopping lists).
With iOS 9.3 they have added the capability to lock individual notes so the content is kept from prying eyes.
This is great. Because Notes is a system app, it's likely to fall to hand for marking down all sorts of information on the phone, some of which the owner might not want others to see. But its implementation of this feature is, well, a bit odd and clunky.
First, the feature has to be turned on in settings, and then an individual note has to have the locking feature enabled by tapping the share sheet. To finalize enabling it, the user has to either enter the password or use Touch ID. All of this is fine, I suppose, though a bit obscure, particularly with the enabling feature in the share sheet menu (which otherwise mostly houses ways to, you know, share things).
What's odd here is that this process enables the lock, but doesn't lock the document. You have to then tap the little lock symbol in the upper right hand corner to formally lock the document. What's more, you also have to do that every time you exit the document in the future.
What I mean is this: Say you go through the process of locking a document, and then go back to read it again, edit it, etc. When you get done with that, and navigate out of the document, it remains unlocked unless you manually choose to lock it. What's more, unlocking that note to edit it also unlocks every other locked note you have in Notes.
To their credit, there is a "lock now" button at the bottom of the document menu screen which, when tapped, locks all open notes. And when I manually lock the note I was working on, it also locks all of the other notes that I inadvertently opened as well. But why this manual process to lock? If I really am protecting sensitive information in a note, wouldn't it be better for it to lock automatically when I exit, always requiring a password or Touch ID to open it again? Then I would know it, and all of my locked notes, are always locked - there would be no need to, say, check to see if my notes were locked before I handed my phone to someone else to look at.
One suspects that this is an attempt to compromise. Other notetaking and writing apps can have a password applied, but this is typically to access the the entire app. Here you can access the Notes application itself without entering a password, but your notes themselves can be protected. One can see the value in that - I can show another person what's on a note without giving them free access to everything I've written. The same cannot be said for an app like Day One, an otherwise excellent journaling program. There, when you enter your password or Touch ID and hand your device to another person you have just granted them free access to anything you've ever written in that app. The Notes solution is better, I suppose, if you want to be able to show others selective information on your device. But honestly, those notes I want secured should automatically secure themselves when I exit them - period.