automatic-ref-counting

An app crashes sometimes with error objc_object::release() . The Apple Developer Technical Support mentioned this: Remember that you should always do something like _tableView.delegate = nil; in your -dealloc methods, even if you are using ARC. For compatibility reasons system objects use unsafe_unretained references to implement delegation, instead of the preferred modern replacement weak . Does that mean that I have to set the delegates of system objects to nil when the view controller is about to be released? class MyViewController: UIViewController { deinit { tableView.delegate = nil

I was able to see an interesting case using Estimote nearables SDK They have a class ESTNearable with property called zone . // ENUM typedef NS_ENUM(NSInteger, ESTNearableZone ) { ESTNearableZoneUnknown = 0, ESTNearableZoneImmediate, ESTNearableZoneNear, ESTNearableZoneFar, }; // CLASS @interface ESTNearable : NSObject <NSCopying, NSCoding> // ... @property (nonatomic, assign, readonly) ESTNearableZone zone; // ... @end So when I try to use this method in Swift , compiler fails with that error: As I understand there is some kind of compiler bug and for some reason it believes that I want to

I am currently playing around with ARC a bit to get some things figured out, before starting to do the actual work. I did setup this code: NSNumber* n = [[NSNumber alloc] initWithInt:3]; __weak NSNumber* weakN = n; n = nil; NSLog(@">>>: %@ %@", n, weakN); I expected n and weakN to be nil, as n = nil; should trigger a release in my eyes? Unfortunately it doesn't. The output is ">>>: (null) 3". What am I missing here? Another thing is, that I am pretty sure, the below code was giving me a hard time when starting with arc: __weak NSNumber* weakN2 = [[NSNumber alloc] initWithInt:3]; NSLog(@">>>: %

dispatch_once call causes crash (in simulator) after I've converted my project to ARC. My original problem was that I've got EXC_BAD_ACCESS (in objc_retain call) crash in one of my singleton object's + (SingletonClass)shared { ... dispatch_once(..., ^{}); ... } method exactly one line before the dispatch_once call. Based on loggings, and breakpoints my code have not run into the dispatch_once call's block. I didn't know the reason, so I've just commented out the dispatch_once call. My app haven't crashed without that call. After that I've tried to put dispatch_once in a method that my app

This is to clear up some doubt in my conceptual understanding of ARC . If ARC is a compile time technology why isnt it available on all versions of iOS and OS X ? ARC isn't just a compile-time technology. It also relies on some runtime components. There's two parts to this: The reference counting. At compile-time, ARC introduces calls to a bunch of helper functions. These are all documented online , but the important ones are objc_retain() , objc_release() , and objc_autorelease() . These do the same things as calling -retain , -release , or -autorelease on the object, but there's some extra

void testFunction (id testArgument[]) { return; } I'm getting the error "Must explicitly describe intended ownership of an object array parameter". Why does ARC need me to specify the ownership type of the objects in the testArgument array? To expand on Jeremy's answer, ARC had two primary goals when designed: make memory management as fully automatic as possible in pure Objective-C code while also preserving or maximizing efficiency (in fact, ARC can be more efficient than manual retain release). require exactly specific declaration of memory management intent when crossing the boundary

My project use ARC. I tested with the code below: NSString __weak *string; @autoreleasepool { string = [NSString stringWithString:@"AAA"]; } NSLog(@"string: %@", string); I think it output as: string: (null) but it actually output: string: AAA I don't understand it. What is the effect of __weak? EDIT: And this code below: NSString __weak *string; NSString __strong *str; @autoreleasepool { str = [NSString stringWithFormat:@"%@", @"AAA" ]; string = str; } NSLog(@"string: %@", string); It also output as: string: AAA NSString __weak *string; @autoreleasepool { string = [NSString stringWithFormat:@