Fix Objective-C/C++ codes to supporting ARC

[2bbb]

this PR makes goal to fix to support all not ARC codes as ARC codes.
please see discussion on: #6848

[ofTheo]

Thanks @2bbb !
Going to ping @danoli3 to take a look too, but as far as I can tell this looks good!

[danoli3]

Looking great @2bbb ! Great work

Maybe just add this to the prime delegate of each platform and not in each obj-c converted but no issues as it's just safeguard

#if !__has_feature(objc_arc)
 #   error need ARC
 #endif

I'll check it out tomorrow and test vs some projects

So far looking good, reviewed changes

[2bbb]

@danoli3

thanks for the comments.

Maybe just add this to the prime delegate of each platform and not in each obj-c converted but no issues as it's just safeguard

OK.
I will remove from .m/.mm and add ARC check macro in ofConstants.h like:

#ifdef TARGET_OSX
	#ifndef __MACOSX_CORE__
		#define __MACOSX_CORE__
	#endif
	#include <unistd.h>
	#include "GL/glew.h"
	#include <ApplicationServices/ApplicationServices.h>

	#if defined(__LITTLE_ENDIAN__)
		#define TARGET_LITTLE_ENDIAN		// intel cpu
	#endif
    
    #ifdef __OBJC__ // added
        #if !__has_feature(objc_arc)
            #error "need ARC"
        #endif
    #endif
#endif

...

#ifdef TARGET_OF_IOS
	#import <OpenGLES/ES1/gl.h>
	#import <OpenGLES/ES1/glext.h>

	#import <OpenGLES/ES2/gl.h>
	#import <OpenGLES/ES2/glext.h>


	#define TARGET_LITTLE_ENDIAN		// arm cpu

    #ifdef __OBJC__ // added
        #if !__has_feature(objc_arc)
            #error "need ARC"
        #endif
    #endif
#endif

I will test too, but do you think is this fine?

[ofTheo]

Could we change:
error need ARC
to something a bit more descriptive?
error Please enable ARC (Automatic Reference Counting) at the project level

[2bbb]

@ofTheo
I will change this message when same as solving @danoli3 point out.

[danoli3]

Looking good, did initial tests. will continue before fully approving

We are now locked to iOS 13 + with inclusion of C++17 filepath just a FYI! No issue with this though!

[danoli3]

Might be a good idea to generate a guide to upgrade a project that is not ARC into ARC oF future though, I had some custom AppDelegates and views that forced into the new ARC realms. Will help devs

[2bbb]

I updated about @danoli3 and @ofTheo point out about ARC feature checking.

[2bbb]

@danoli3

962432e

I added some comments (can search with TODO:) for some points about delegate/protocol.
Those need to change with some non-trivial complexity and are worried about compatibility, I want to update after this PR (about ARC).
If you are interested in, please check it.

[2bbb]

I think what replacing many pairs of an explicitly defined instance variable, @property and @synthesize to @property including implicitly defined instance variable and removing @synthesize is better to Maintainance.
because currently, if we need to change type of variable then we need to change two points, but if there is only one @property then we need to change once.

I will do this with other PR after this PR is finished.

[ofTheo]

Going to leave @danoli3 to okay the final merge of this!
@danoli3 just make sure to do Squash and Merge above with #changelog #osx #ios #tvos ( this helps with generating the changelog for releases )

[danoli3]

Looks good! For anyone with issues with old non-arc code that cannot be converted: You can add this to compile flag per src file

-fno-objc-arc

[danoli3]

Been testing looks good

[danoli3]

Good to merge @ofTheo

[ofTheo]

Thanks @2bbb @danoli3

[dimitre]

Hello @2bbb I've tried to port ofxSyphon to ARC with no success.
As I need it for several projects I should change XCode project to disable ARC and comment out a line in ofConstants.h
My suggestion is we can disable ARC enforcing now in ofConstants.h as everything else works great anyway.
cc: @ofTheo

[2bbb]

Hi, @dimitre

I changed about those on 96f11b8
but this was wrong.

maybe correct way is what condition macro is wrote in all .m / .mm file, or make one header and include from those files.
at least it was a completely mistake to put them together in ofConstants.h...