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The Castro Manifesto

Posted by Padraig on Dec 10, 2013

Castro enters a crowded market at an interesting time. iOS has radically changed direction and the old consensus of what makes a great app is no longer a reliable guide. Why make a podcast app now? Our objectives for Castro arise from frustrations with the apps currently available, new opportunities afforded by iOS 7, and a desire to prove that independent software developers can still make it on the App Store.

As we progressed through the development cycle, we started to figure out what principles were important in an app like this. Here is a quick overview of the main points. We hope to expand upon these more fully over the next few weeks.

Approach iOS 7 with an open mind

We aimed to understand iOS 7 design and not to get bogged down in the differences between it and previous versions. Many post-WWDC design criticisms were nuanced, clever and even objectively true, but the software has shipped and the users have not rebelled. The framework for the next 5 years has been set. Castro does not have an iOS 6 ancestor: it is iOS 7 all the way down.

Podcasts are entertainment

A subscription is not a commitment to listen to every episode. The list of unplayed episodes should never become another inbox to feel bad about. Castro does not have unplayed episode counters, blue dots, or red badges.

An app should have a clear navigation hierarchy

Starting from any place in the app, the user should be able to orient themselves instantly. Castro applies podcast artwork to brand the interface, thereby providing context for the user. Gestures are used for navigation between screens and by eliminating the navigation bar, more screen space is available to showcase the content. Just as iOS has always had full screen apps that become the device when launched, we wanted full screen podcasts that become the app when opened.


Apple resists power user features if they compromise the experience of a regular user.

Most of the chart topping podcast apps do the opposite. Every feature imaginable is implemented and everything is a setting. Over time these apps have become a suite of tools for empowering engineering-minded users to obsessively chase the perfect podcast workflow. To the extent that these users can be accommodated, they already are.

We believe that there is a sizeable group of people who will prefer a simple, well thought-out flow. Castro will serve these people well.

Novelty vs Gimmicks

There are practical motivations to the use of novel interactions and design in Castro. The scrubber, for example, addresses specific defects: the default scrubber is hard to grab, fingers can obscure the play position, and despite rarely being needed, it’s always on screen. In Castro, the small player bar defers space to the show notes, while also making scrubbing easier.

The interface uses tint colours and podcast backgrounds not only to celebrate great podcast artwork but also to provide spacial context at a glance. Castro uses interactive transitions to maintain this context.

Castro gains more space to fit longer titles by dropping the navigation bar. Auto Layout gave us the flexibility to give content the room it needs.

The iPhone Is Not A Dumb Terminal

The limitations of previous iPhones and iOS versions almost necessitated the use of a server to do heavy lifting, not the device itself. The platform has however passed a tipping point in processing power, internet speed, and software capability. There are new opportunities for developers who are willing to reconsider the assumptions that have shaped app development over the last 5 years.

Castro does not use a server to manage subscriptions or notifications. It uses the iTunes Search API to find podcasts; It requests podcast feeds directly from their hosts. Castro uses the background fetch API to check podcast feeds regularly. It then alerts the user with a local notification when it finds a new episode.

Castro is not dependent on new sales to continue operating because there are no server costs. This app will continue to work in the future as it does today. Customers pay for the app itself, not for a backend web service or monthly server fees. Castro is a rare example of an app that naturally fits the App Store pricing model.


Castro is not an “opinionated” app. We did not design it around one individual’s obscure idea of their own ideal flow. We developed the app with the generous help of many volunteer testers. Between the two of us, we have collectively invested a year of full time work to complete Castro 1.0 and we look forward to working on it for years to come.

We hope you like it.

Pádraig and Oisín

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