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objective_c

A library to access Objective C from Flutter that acts as a support library for package:ffigen.

This library isn't very useful on its own. Typically it is used while interoperating with an Objective C library created by package:ffigen. See https://pub.dev/packages/ffigen

For general information about interop with Objective C, see https://dart.dev/guides/libraries/objective-c-interop

Memory management

Objective C and Dart use different styles of memory management. Dart is garbage collected, while Objective C uses reference counting. This difference is a common cause of bugs when interoperating between the two languages.

Memory management issues typically manifest as seg faults, which can be hard to debug as they often have no useful stack trace. The most common issue is use after free errors, where a Dart object is constructed to wrap an Objective C object that has already been destroyed. To debug these issues, try running your program with asserts enabled. When the Dart wrapper object is created or destroyed, an assert checks that the Objective C object still exists, which should provide a much more useful stack trace.

References are automatically retained when the Dart wrapper object is created, and released when the Dart object is garbage collected. But to fix a reference counting issue, it may occasionally be necessary to manually control the ref count. The ref count of the Objective C object can be controlled from Dart by the retain and release options in the Dart wrapper object constructors, and by the retainAndReturnPointer() and release() methods.