ARC-Safe Memory Management

By Karl Stenerud

Makes your code both ARC and non-ARC compatible!

Introduction

Automatic Reference Counting is awesome stuff, but it's going to take awhile for most projects to fully make the transition. This can cause problems when using outside code, especially when you have to mix and match ARC and non-ARC.

To make things easier for users of your code snippets, libraries and APIs, make them compilable BOTH ways and let the user decide whether to use ARC or not!

Features

Ownership management macros
Property and storage qualifiers
Bridging between retainable and non-retainable pointers
Autorelease pools (for GCC support)

Usage

Import:

#import "ARCSafe_MemMgmt.h"

Ownership Management:

// Each of these only produce code when compiled without ARC.

// Retain an object
myRef = as_retain(someObject);

// Release an object
as_release(someObject);

// Autorelease an object
myRef = as_autorelease(someObject);

// Autorelease, but don't return a reference to the object
as_autorelease_noref(someObject);

Dealloc Support:

- (void) dealloc
{
    // Calls [_myIvar release] when in non-ARC.
    as_release(_myIvar);
    
    // Calls [super dealloc] when in non-ARC.
    as_superdealloc();
}

Property Qualifiers:

// Note: Weak references are not supported prior to iOS 5!
@property(as_weakprop, nonatomic, readwrite) id weakProp;
@property(as_strongprop, nonatomic, readwrite) id strongProp;

Storage Qualifiers:

// Note: Weak references are not supported prior to iOS 5!
id as_weak weakValue;
id as_strong strongValue;
id as_unsafe_unretained unsafeUnretainedValue;
id as_autoreleasing autoreleasingValue;

Bridging:

CFErrorRef errorRef = CFErrorCreate(NULL, (as_bridge CFStringRef)domain, 1, (as_bridge CFDictionaryRef)userInfo);
*error = as_autorelease((as_bridge NSError*)errorRef);

Autorelease Pools:

Note: These are only needed if you want your code to be compilable under the GCC compiler. If you only plan to support CLANG, use @autoreleasepool.

as_autoreleasepool_start(pool_a);

...

as_autoreleasepool_end(pool_a);

Full Example

I've included a full example project in this repository. See ViewController.h and ViewController.m for details.

You can test compatibility by turning "Objective-C Automatic Reference Counting" on/off in the build settings, and changing between "Apple LLVM Compiler" and "LLVM GCC".

License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall remain in place in this source code.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.