Please follow Originate's Objective-C style guide.
Other popular style guides for reference:
Introduction of ARC
In 2011, Apple introduced automatic reference counting (ARC) as the memory management model for Objective-C code. ARC is available beginning with Xcode 4.2 / iOS 5.
All new codebases should use ARC, but older/legacy code may still utilize manual retain-release (MRR).