Language Versions

Note: Versions before Stepstone 4.0 are missing.

Note: In order to solve the confusing versioning scheme of Objective-C, this document uses its own versioning scheme which is similar to the current, extremely vague scheme.

References

Compiler release notes for NeXT Releases 3.0 to 3.3

Assembler, linker, etc release notes for Rhapsody 5.0 to Xcode 3.2.1

Objective-C Release Notes (Mac OS X Leopard)

spec.language, a Stepstone-internal document detailing planned user-visible changes to Stepstone Objective-C 4.0

Objective-C Feature Availability Index

What’s new in Xcode 4

v0.8 - Lowest Common Denominator

Availability

Compilers

  • Stepstone >= 4.0

  • Portable Object Compiler

  • NeXT GCC fork

  • GCC since around 1992

  • Clang

Runtimes

  • Stepstone >= 4.0

  • Portable Object Compiler

  • NeXT/Apple with 32-bit ABI

  • Apple with modern ABI

  • GCC runtime

  • GNUstep runtime

Available features

  • #import preprocessor directive

  • @interface…@end class declarations

  • @implementation…@end class definitions

v0.9 - Categories

Availability

Compilers

  • NeXT GCC fork (was available sometime before 3.0)

  • GCC (all versions with documentation on the GCC website)

  • Clang

  • Portable Object Compiler

Runtimes

  • NeXT/Apple with 32-bit ABI

  • Apple with modern ABI

  • GCC runtime

  • GNUstep runtime

  • Portable Object Compiler

New features since v0.8

  • Major feature: Categories

v0.10 - NeXT Release 3.0

This release introduces some C99 features.

Availability

Compilers

  • NeXT GCC fork >= 3.0 (based on GCC 1.93)

  • GCC >= 2.0

  • Clang

Runtimes

  • NeXT/Apple with 32-bit ABI

  • Apple with modern ABI

  • GCC runtime

  • GNUstep runtime

Major new features

  • Protocols

    • @protocol…@end

    • <…> syntax for declaring classes

    • New qualifiers for types that can only be used in protocol declarations: in, out, inout, bycopy, oneway.

  • Interface variable access control

    • @public variables are accessible by anyone

    • @protected variables are accessible by defining class and subclasses

    • @private variables are only accessible by the defining class

    • default is @protected

Changes since v0.9

  • Forward declaration of classes (@class)

  • #warning directive to complement #error

  • __attribute__:

    • aligned

    • format

  • New @encode encodings for in, out, inout, bycopy, oneway, const.

v1.0 - Exceptions and synchronization

Availability

  • GCC >= 4.0 with -fobjc-exceptions command line argument

  • Clang

New features

  • Exceptions

  • Synchronization

Notes

  • On GCC, you can use the fobjc-std=objc1 to disable Objective-C 2.0.

References

v2.0 - 2007 - Leopard

Availability

Compilers

  • Xcode >= 3.0

  • GCC >= 4.6

  • Clang >= 1.0

Runtimes

  • Apple runtime >= (10.5 Leopard)

  • GCC runtime >= GCC 4.6

  • Etoile runtime

  • GCC runtime with ObjectiveC2.framework

  • GNUstep runtime (all versions)

Major new features

  • Garbage collection

    • Didn’t really take off, was replaced by Automatic Reference Counting

    • Not supported anywhere anymore

    • Different from GNUstep garbage collection

  • Properties @property

    • Automatic getter and setter generation @synthesize

    • Dot notation object.count instead of [object count] and [object setCount: ]

  • Non-fragile ivars (requires runtime support)

  • Fast enumeration for (id thing in myList)

  • properties (via the @property, @synthesize and @dynamic keywords), fast enumeration (not available in Objective-C++), attributes for methods (such as deprecated, noreturn, sentinel, format), the unused attribute for method arguments, the @package keyword for instance variables and the @optional and @required keywords in protocols

Resources

v2.1 - 2011 - ARC, Xcode 4.2

Availability

Compilers

  • Xcode >= 4.2

  • Clang (upstream) >= 3.0

    • Apple LLVM Compiler >= 3.0

Runtimes

  • Apple runtime >= (Mac OS X 10.7 / iOS 5)

  • GNUstep runtime >= 1.6

Major new features

ARC, @autoreleasepool, completely private ivars

  • Automatic Reference Counting (ARC) and an improved memory model cleanly separating object and C memory.

  • A migration tool for moving manual retain/release code to ARC

  • Better support for data hiding, allowing instance variables to be declared in implementation contexts or class extensions

  • Weak linking support for Objective-C classes

  • Improved static type checking by inferring the return type of methods such as +alloc and -init.

Resources

v2.1.1 - 2012 - Xcode 4.3

v2.2 - 2012 - Literals, Xcode 4.4

  • Literals syntax is supported for NSArray, NSDictionary, and NSNumber objects, using the same @ operator as for NSString literals.

  • Subscripting is enabled for Objective-C containers, including NSDictionary and NSArray. Use the [ ] syntax convention.

  • Objective-C @properties are synthesized by default when not explicitly implemented.

v2.3 - Xcode 6.3

Availability

Compilers

  • Xcode >= 6.3

  • Clang >= 3.6.0

    • Apple LLVM Compiler >= 6.1.0, clang-602.0.49

Runtime

The new features require no runtime support.

New features

References

v2.3.1 - 2015 - Xcode 7.0

Availability

Compilers

  • Xcode >= 7.0

  • Clang >=

Runtime

The new features require no runtime support.

New features

  • Nullability specifiers are now _Nullable, _Nonnull, and _Null_unspecified instead of __nullable, __nonnull, and __null_unspecified

  • Lightweight generics

  • Kindof types

References

Unknown 2.x

https://developer.apple.com/library/archive/releasenotes/ObjectiveC/ModernizationObjC/AdoptingModernObjective-C/AdoptingModernObjective-C.html

  • instancetype

  • Enumeration macros

  • Designated initializers