iOS should present a default device owner’s avatar image to any apps that request one.
Getting started on any new social media platform – or on one of the majority of apps which increasingly require an initial login to create a presence within the app’s community – is now a pretty efficient and streamlined process. If you do not want to login with your Facebook or Twitter identity credentials  then you just need to provide a user name and a password (sometimes an email address is not even needed any more) and you are good to go. You get a generic avatar icon to speed your way directly into the service: completing your user profile by adding a photo and any other information can always happen at any time later on. Because including your avatar photo is not a step within that initial on-ramping workflow one can see a lot of default avatars being used in the early stages of community building.
In the last year I have started using one consistent headshot icon across all of my social media accounts. (Currently it is my eight-bit alter ego from some ZX Spectrum-themed alternate universe.) I think it is a useful idea to present a standardised visual to all of my various audiences and communities. That must be my background in corporate identity coming through...
It strikes me that it would be a useful feature in iOS if I could identify one image file as my default avatar for all new social media services, and more broadly all of those apps that require a login and that create a presence for users.
I imagine most people do not store a dedicated image file within their Camera Roll for such a purpose. Which is the hack I need to do at present. Surely the underlying iOS can help users out here?
The personalised owner’s entry in the Contacts.app seems to be the obvious starting point within the current system. I would add an option in the ‘Edit’ pane for the user’s personalised headshot that then presented this image as a default avatar for any apps that requested one. An Auto-Complete for avatar images if you will. Then, whenever setting up relevant apps, the iOS could present a relevant dialogue box with a “Use This Photo” option to securely evoke the default image without exposing any confidential information and a “Take Photo” option to evoke the camera.
Finally, I have never been convinced with the current iOS configuration of treating your own information as just another entry within Contacts.app. There is a logic and simplicity to this approach in one sense, but I can envisage some kind of centralised, dedicated and enhanced ‘My Information’ or ‘My Identity’ section in Settings that would allow for increasing connectivity and granular access of the iPhone owner’s information with the various clouds and super-platforms. Today our phones primarily identify us and accredit us to services like social media, but in the future they will allow us to pay for goods and services, travel on public transport, even unlock our front doors etc. How our phones handle our identity is going to become increasingly important.
 Thinking about this further, now that Twitter is so tightly integrated into iOS perhaps Apple really do want us to adopt that as our identification layer for apps. If I were to set up all apps using my Twitter accreditation in future, I would not need a dedicated avatar image to be served by the OS. But, down the line, I do not see myself logging-in to my secure digital wallet or to my home security system with my Twitter credentials. Do you?