How to know if my Xcode iPhone project is using ARC? - iphone

I want to know if my Xcode iPhone project is using ARC, and I can't remember if I ticked that box when creating the project.
How can I get this information?

Select your project, then Build Settings. Look for Objective-C Automatic Reference Counting in the Apple LLVM Compiler - Language section. Make sure you select the target; while you can set this in the project, the target can override it.
(You can also use the search bar in Build Settings for OBJC_ARC.)
Keep in mind, too, that you can turn ARC on or off on a per file basis in build phases.
Or, just try something like this in code:
[[[NSObject alloc] init] autorelease]
If you get an error:
ARC forbids explicit message send of 'autorelease'
Then you're using ARC.
You can also require ARC from a source code file by checking for it:
#if !__has_feature(objc_arc)
#error This file must be built with ARC.
// You can turn on ARC for only this file by adding -fobjc-arc to the build phase.
#endif

Just search for Automatic in your target's build settings:

Related

How can I remove ARC from iPhone project build for iOS 5?

Now I have a Xcode project which is built for iOS 5, but now i have to install it on an iPhone 3GS, which has a older iOS. I came to know that this is because I am using ARC in this project and it is not available in iOS 3.2. How can I remove ARC from my current project?
If you want it disabled for the whole project, you need to go to the target's build settings and set it to No
very simple first go to targets in that go "buldphases"-->compileSource--> here "yourfile.m" --> set value
-fno-objc-arc(only particular files )
if u want remove ARC in entire project go to targets in that go "buldsettings" ---> objective-c automaticrefcount :NO
In XCode, there is a global compiler flag called -fobjc-arc. If you disable this (-fno-objc-arc), ARC will be disabled in your whole project. If only a few files don't support ARC, use the -fno-objc-arc flag on those files only. The last flag "wins", see http://clang.llvm.org/docs/AutomaticReferenceCounting.html#general.
However, make sure that you know what you're doing! If the project was designed around ARC, there may not be any deallocation-code in there, including dealloc methods. Also, your properties might be unsupported (strong, weak etc.). You'll most likely end up in a complete mess.
Your best bet would be to just upgrade your 3GS.
Go
Build Settings
make sure "all" option is selected
search for automatic you will find Objective-c Automatic Reference counting set NO

Use Automatic Referencing Count in specific classes in ios

Actually i came to this question when i was trying to add some classes that have been made upon ios prior to IOS 5 and these classes doesn't having ARC and the project i am trying to add is made upon the IOS 5 and it give me the compile time error related to ARC the classes having suck kind of information that if i try to remove the release/retain then it start behaving irregular.That is my problem, Now come to question i want to know that is there any way so that i can mark those classes not to use ARC so that the newly created classes that having base SDK ios5 compile with ARC and i mention not to use ARC simply compiled with their retain/release values.That is the only way i have left i think for making properly this app.
Any idea how i can use those classes that is having base sdk prior to ios5.
Thanks,
the image below will show you how to do it.
-fno-objc-arc flag to disbale arc
-fobjc-arc flag to enable arc
Go to your project settings, under Build Phases > Compile Sources
Select the files you want ARC disabled and add -fno-objc-arc compiler flags. You can set flags for multiple files in one shot by selecting the files then hit Enter key.
Go to Issue Navigator -> Validate project settings -> Perform changes. In this way Xcode automatically remove release and retain keywords from whole project and convert into ARC compatible.

How to add ARC for specific file?

I created a project without ARC. I want to use a third party SDK in my project. That SDK comes with ARC Support. So I want to add ARC for that third party files. I can disable ARC for all "MYProject" files by adding this flag into build phases like -fno-objc-arc.
But I may use large number of files. So it's better to add ARC for specific SDK only. So how to add ARC support for single or specific SDK files in XCode Project?
For Instance: I want to use Grid View. I'm adding GMGridView in my project and it comes with ARC support.
Add the flag -fobjc-arc to the files that you'd like to use ARC. It's just the opposite of the other.
You add compiler flags in Targets -> Build Phases -> Compile Sources
Compile source show all file that project contain.so please add -fobjc-arc to compiler flag by double clicking on it as show in below image.

Files doesn't support the ARC feature, how to deal with

My project uses the ARC(Automatic Reference Counter), so when i try to import the ASIHTTPRequest library which has 4 classes that used in their implementation the autorelease statement, here is an example:
[self setAccessLock:[[[NSRecursiveLock alloc] init] autorelease]];
The error that i got:
ARC forbids explicit message send of autorelease
What should i do to solve this problem.
I have got the solution, i needed to add the right flags to the compiler flags for each file which doesn't support the ARC. For me, i use Xcode 4.2, so under target -> Build Phases -> Compile Sources, double click on the file you want to disable the ARC feature and put -fno-objc-arc the click on Done. And it's Done ;)
Please note, that if the file doesn't exist on the list, you can just add it by clicking the + button and then perform the same work above.
Disable ARC for that one class
When you migrate a project to use ARC, the -fobjc-arc compiler flag is set as the default for all Objective-C source files. You can disable ARC for a specific class using the -fno-objc-arc compiler flag for that class.
In Xcode, in the target Build Phases tab, open the Compile Sources group to reveal the source file list. Double-click the file for which you want to set the flag, enter -fno-objc-arc in the pop-up panel, then click Done.

Convert App to ARC while ignoring files?

I want to convert my app to ARC but I have some external librarys and frameworks that are not complaint with ARC. I know when yous start a new project using ARC, you can later specify which files to ignore. But can you do this when upgrading an existing app to ARC?
in XCode, go to your active target and select the Build Phases tab. In the Compiler Flags column, set -fno-objc-arc for each of the files you don't want ARC
EDIT:
Also, to have the opposite behavior, I mean to use a file that was written using ARC inside a non ARC project, you can set the file flag to -fobjc-arc instead
There is plenty of more info regarding ARC here: http://clang.llvm.org/docs/AutomaticReferenceCounting.html#general
ARC may be explicitly enabled with the compiler flag -fobjc-arc. It may also be explicitly disabled with the compiler flag -fno-objc-arc. The last of these two flags appearing on the compile line "wins".
Source: http://clang.llvm.org/docs/AutomaticReferenceCounting.html
To add to Felipe's answer, if you want to add this to multiple files at once:
Select all the files you want to exclude form ARC
Press 'Enter'
The pop-up box will appear at the last file in the list
Type -fno-objc-arc