You can find discussions about almost anything on social media, and iOS development is no exception. All the major services have groups, areas, and/or people. Again, you can do searches on your favorite places. And this section lists some to get you started.
LinkedIn has a number of dedicated and related discussion groups, some open and some moderated, including these:
All the subgroups of “iPhone OS Developer Network”
Cocoa and Cocoa Touch Developers
Facebook has groups, though not a lot of them are technical, and ...