In terms of language features, mulle_objc resets the basis of Objective-C back to ObjC 1.0 and cherrypicks improvements from the later versions.
Differences to Objective-C 2.0
Do not use the “not planned” features even if the mulle-objc compiler might still understand them. The runtime or the linker will not support them.
| Topic | State | Link | |
|---|---|---|---|
| @encode() | supported: 90% the same as the Apple runtime | ([what is this ?](https://nshipster.com/ | type-encodings/)) |
| @package | never: will produce an error | ||
| @synchronized() | not planned | (what is this ?) | |
| ^blocks | not planned: [^3] | ([what is this ?](https://medium.com/@amyjoscelyn/ | blocks-and-closures-in-objective-c-2b763e9e0dc8)) |
| atomic | not planned: atomic as default: never | ||
| BOOL | supported: but it is an int. If you really need to use bool use _Bool. |
||
| @import | not planned | ([what is this ?](https://stoneofarc.wordpress.com/2013/06/25/ | introduction-to-objective-c-modules/)) |
| nullable | not planned: will produce an error [^2] | ||
| readonly | supported: but an ivar will be synthesized | ||
| weak, strong | never | ||
__bridge |
will be a nop #define (also __bridge_retained, __bridge_transfer) |
||
__unsafe_unretained |
could be a nop #define (_autoreleasing) |
||
| ARC | never: but look for mulle-objc’s AAM | ([what is this ?](https://www.yorkhua.com/ | objective-c-arc/)) |
| @implementation() | never: class extension with added instance variables don’t work | ||
| NSArray<NSString* > | never: generics are not in the cards | ([what is this ?](https://www.thomashanning.com/ | objective-c-lightweight-generics/) |
| ObjectiveC++ | never: But the mulle-objc instance memory layout should be this->__vtab compatible to |
allow dual facing objects. | |
| NSArray *foo; foo[ 1] | not planned: [^1] what is known as “Subscripting” | ([what is this ?](https://nshipster.com/ | object-subscripting/)) |
| Non-fragile ivars | never | ([what is this ?](https://www.sealiesoftware.com/blog/archive/2009/01/27/ | objc_explain_Non-fragile_ivars.html)) |
| property dot syntax | not planned: [^1] | ([what is this ?](https://stackoverflow.com/questions/7423853/ | whats-the-difference-between-dot-syntax-and-square-bracket-syntax)) |
| Protocol | never: Protocol as a class is gone. You have to use PROTOCOL instead of Protocol * |
||
| variadic arguments (:…) | supported: but not compatible to <stdarg.h> |
| Topic | State | Link |
|---|---|---|
NSLog |
generally not used anymore, use mulle-printf instead |
Appendix
Footnotes
[^1] : This is basically operator overloading, which is un-C like.
[^2] : Superflous keyword, ObjC is by design nullable. It only makes sense to adorn non-nullable parameters.
[^3] : GCD is a Apple technology, that really needs kernel support to work well. lambdas are not a part of C11. Generally I find blocks unconvincing. It might be an idea to make NSInvocations out of block syntax ?
Glossary
| Wording | Meaning |
|---|---|
| not supported | might just accidentally work |
| not planned | never say never, but this probably won’t happen |
| never | sometimes you have to say never :) |
Terminology
For the discussed concepts and terminology check any of the following links.
- Wikipedia: Objective-C
- Apple: Objective-C Feature Availability Index
- NSHipster: @compiler directives
Next
With all the theory under your belt, you’re ready to start your own project.