12. Extensions

Since the dawn of the iOS platform, apps have been sandboxed. Third-party apps could not influence any other app with the exception of some simple URL scheming. With the introduction of iOS 8, Apple has given developers the ability to run code from their apps outside of the sandbox for the first time. Although extensions are limited in functionality, they add a great amount of flexibility to the developer’s tool belt. Six types of extensions are available on the iOS platform (Finder Sync is uniquely OS X), each with its own specific function. This doesn’t include Apple’s choice to use extensions to power WatchKit, which is discussed in the “Apple Watch Extension” section of this chapter.

This chapter covers two of the most popular ...

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