Chris Dzombak

Greg Titus on NSFileCoordination and Extensions

Update 2014-12-01: TN-2408 explicitly says you shouldn’t use NSFileCoordination for app↔extension coordination:

Using file coordination in an app extension to access a container shared with its containing app may result in a deadlock. This is usually the case if a process is suspended mid coordinated I/O. This can be more prevalent on iOS where most apps will be suspended after a short period of time after being moved to the background. Extensions should use alternatives to file coordination.