Please check the build logs for more information.
See Builds for ideas on how to fix a failed build, or Metadata for how to configure docs.rs builds.
If you believe this is docs.rs' fault, open an issue.
objc-sys
Raw Rust bindings to the Objective-C runtime and ABI.
Runtime Support
Objective-C has a runtime, different implementations of said runtime exist, and they act in slightly different ways. By default, Apple platforms link to Apple's runtime, but if you're using another runtime you must tell it to this library using feature flags.
Apple's objc4
- Feature flag:
apple
.
This is used by default on Apple platforms when no other feature flags are specified.
The supported runtime version (higher versions lets the compiler enable newer
optimizations, at the cost of not supporting older operating systems) can be
chosen using the standard X_DEPLOYMENT_TARGET
environment variables:
- macOS:
MACOSX_DEPLOYMENT_TARGET
- Default:
10.7
(same as Rust) - Minimum:
10.7
- Default:
- iOS:
IPHONEOS_DEPLOYMENT_TARGET
- Default:
7.0
(same as Rust) - Minimum:
5.0
(theoretically)
- Default:
- tvOS:
TVOS_DEPLOYMENT_TARGET
- Default: TODO
- Minimum:
9.0
(theoretically)
- watchOS:
WATCHOS_DEPLOYMENT_TARGET
- Default: TODO
- Minimum:
1.0
(theoretically)
A git mirror of the sources is available here.
GNUStep's libobjc2
- Feature flag:
gnustep-1-7
,gnustep-1-8
,gnustep-1-9
,gnustep-2-0
andgnustep-2-1
depending on the version you're using. Recommended default isgnustep-1-8
.
Window's WinObjC
- Feature flag:
winobjc
.
This is essentially just a fork based
on GNUStep's libobjc2
version 1.8, with very few user-facing changes.
ObjFW
(WIP)
- Feature flag:
objfw
.
TODO.
Other runtimes
This library will probably only ever support "Modern" Objective-C
runtimes, since support for reference-counting primitives like objc_retain
and objc_autoreleasePoolPop
is a vital requirement for most applications.
Just so we're being clear, this rules out the GCC libobjc
runtime (see this), and the mulle-objc
runtime. (But
support for ObjFW
may be added). More information on different runtimes
can be found in GNUStep's Objective-C Compiler and Runtime FAQ.
Advanced linking configuration
This crate defines the links
key in Cargo.toml
so it's possible to
change the linking to libobjc
, see the relevant cargo docs.
In the future, this crate may vendor the required source code to automatically build and link to the runtimes. Choosing static vs. dynamic linking here may also become an option.
Objective-C Compiler configuration
Objective-C compilers like clang
and gcc
requires configuring the calling
ABI to the runtime you're using:
clang
uses the-fobjc-runtime
flag, of which there are a few different options.gcc
uses the-fgnu-runtime
or-fnext-runtime
options. Note that Modern Objective-C features are ill supported.
This is relevant if you're building and linking to custom Objective-C sources
in a build script. To assist in compiling Objective-C sources, this crate's
build script expose the DEP_OBJC_CC_ARGS
environment variable to downstream
build scripts.
Example usage in your build.rs
(using the cc
crate) would be as follows:
Design choices
It is recognized that the most primary consumer of this library will be macOS
and secondly iOS applications. Therefore it was chosen not to use bindgen
in
our build script to not add compilation cost to those targets.1
Deprecated functions are also not included for future compability, since they could be removed in any macOS release, and then our code would break. If you have a need for these, please open an issue and we can discuss it!
Some items (in particular the objc_msgSend_X
family) have cfg
s that prevent
their usage on different platforms; these are semver-stable in the sense
that they will only get less restrictive, never more.
1 That said, most of this is created with the help of bindgen
's
commandline interface, so huge thanks to them!