App extensions are the beginning of sharing data between iOS apps. It comes with it's own challenges especially with file synchronization and read-write operations. Tom provides a good understanding of what it takes to use share data between apps with code samples.
Sam explaining not what optionals but why they are. I love this kind of posts, it's important to know why certain programming constructs exists so we can use them effectively.
If you are looking to make awesome app preview videos and do it as a developer will do it, Chris has the right library for you. This post also gives a good rundown of how to use AVFoundation library.
And now that the WatchKit is out we have a better view of designing watch apps. Notably, WatchKit removes autolayout and introduces Groups that handle the layout of elements inside.
This is an answer to all the fights on evaluating design. I personally would love to have this list handy to avoid unnecessary discussion. Reminds me of the book - The Checklist manifesto, it recommends using a checklist at the time of any medical procedure so all the bases are covered.
In this post Achin suggests using MessageBus to loosely coupled code. Write code for reusability is tricky because you can go too far and spend a lot of time. A tried and tested approach helps us avoid pitfalls.
With the arrival of ART compiler with Android L we should know the difference between the two and why the switch happened. Aayush helps us with the benchmark numbers and features of ART compiler in this post.
Probably the most used app, Google Maps has been redesign with Material Design. This is the official google blog post explaining specific design elements.
An app with very minimal functionality such as Yo app needs integration with other apps. Design is critical there to make it available whenever use needs it like when browsing contacts etc. Raveesh has some recommendations for us in this post.