In Xcode we enjoy some automatic analyzer features to find memory leaks for CoreFoundation and Cocoa object. I used them in the past to find leaks related to various objects in the code for MBS Xojo Plugins. In the last months, I got to use these for our Xojo objects and strings.
I defined my own function annotations to inform the compiler whether the function returns a REALobject or REALstring with +1 reference count or +0 reference count.
To give you an idea how many annotations I needed, here are the numbers:
| REALOBJECT_RETURNS_RETAINED | 13012 |
|---|---|
| REALOBJECT_RETURNS_NOT_RETAINED | 17 |
| REALSTRING_RETURNS_RETAINED | 2814 |
| REALSTRING_RETURNS_NOT_RETAINED | 7 |
Once the annotations work, we use analyze command in Xcode to find issues. I setup an example for you:
The functions NewDictionary, REALNewVariantString, REALNewVariantInteger, CString2RB and many others are annotated to return a retained object. Xcode can report that we allocated a dictionary, a string and objects in the method. And since we don’t free them, it can complain.
Adding this took months and on the way, I found a couple of memory leaks. Mostly in edge cases where memory was not released property on case of an exception or with a lot of nested branches.
In future we will enjoy this and I hope it helps us ship less memory leaks.