Your code will work fine: the weak reference will not cause a retain cycle as you explicitly instruct ARC not to increase the retainCount of your weak object. For best practice, however, you should create a strong reference of your object using the weak one. This won’t create a retain cycle either as the strong … Read more
Consider how ARC works with variables – each reference variable has a mode (implicit or explicit): strong, weak, etc. This mode let’s ARC know how to handle reads and writes to that variable; e.g. for a strong variable reading requires no additional action while writing requires releasing the existing reference in the variable before it … Read more
As mentioned in the comments, I think it’s fine to talk about ARC and the contents of Automatic Reference Counting here. __autoreleasing is not meant to be used like that. It’s used for passing indirect object references (NSError**, etc). See 4.3.4 Passing to an out parameter by writeback. According to 3.2.4 Bridged casts, the __bridge_transfer … Read more
You should explicitly remove the observer even you use ARC. Create a dealloc method and remove there.. -(void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; } If you see the method you don’t need to call [super dealloc]; here, only the method without super dealloc needed. UPDATE for Swift You can remove observer in deinit method if you … Read more
ARC needs to know the ownership of an object reference so it can determine when to release it etc. For any variable (local, instance or global) ARC has rules for determining the ownership; either by inference or by an explicit attribute. This equates to the pre-ARC need for the programmer to track ownership. But what … Read more
It’s mostly right, but assign properties are still treated the same as they ever were, only weak ones are zeroing. Another caveat is that zeroing weak references are only available in Mac OS X ≥ 10.7 and iOS ≥ 5. While the rest of ARC was backported to 10.6 and iOS 4, weak references cannot … Read more
“ivar” means “instance variable”, which you have not shown. I’m betting it looks something like this: @interface Foo : NSObject { id delegate; } @property (weak) id delegate; What the error is saying is that it must look like this: @interface Foo : NSObject { __weak id delegate; } @property (weak) id delegate; If the … Read more
This is indeed a new language feature, and if you must declare your ivars (rather than simply declaring properties and letting the compiler generate ivars for you) it’s a good practice. Your header files in theory should only expose public interface for your classes; everything else belongs in the implementation. One caveat is that implementation-file … Read more
Click on you project, in the left hand organizer. Select your target, in the next column over. Select the Build Settings tab at the top. Scroll down to “Objective-C Automatic Reference Counting” (it may be listed as “CLANG_ENABLE_OBJC_ARC” under the User-Defined settings group), and set it to NO. This is on Xcode 4.2 (Build 4D199).
Use direct access in partially constructed states, regardless of ARC: – (id)initWithReminder:(Reminder*)reminder_ { self = [super init]; if (self) { reminder = reminder_; // OR reminder = [reminder_ retain]; } return self; } This is because self.whatever will trigger other side effects, such as Key-Value Observing (KVO) notifications, or maybe your class implements (explicitly) or … Read more