Turns out, I’ve written some serious nonsense If zombies worked like I originally wrote, turning on zombies would directly lead to innumerable false positives… There is some isa-swizzling going on, probably in _objc_rootRelease, so any override of dealloc should still be called with zombies enabled. The only thing that won’t happen with zombies is the … Read more
The problem with performSelector is that ARC doesn’t know what the selector which will performed, does. Consider the following: id anotherObject1 = [someObject performSelector:@selector(copy)]; id anotherObject2 = [someObject performSelector:@selector(giveMeAnotherNonRetainedObject)]; Now, how can ARC know that the first returns an object with a retain count of 1 but the second returns an object which is autoreleased? … Read more
You can’t release mimeType because you don’t own it. You didn’t transfer ownership with the __bridge cast. You should be releasing uti since you have created it. You should also release extension since you created it as well, but that will likely cause issues with ext. Instead, transfer ownership to ext. I’d suggest the following: … Read more
I tried this […] lazy var personalizedGreeting: String = { return self.name }() it seems there are no retain cycles Correct. The reason is that the immediately applied closure {}() is considered @noescape. It does not retain the captured self. For reference: Joe Groff’s tweet.
Tutorial for Xcode 4 Create new project and add the following to AppDelegate.h and AppDelegate.m. AppDelegate.h #import <Cocoa/Cocoa.h> @interface AppDelegate : NSObject <NSApplicationDelegate> { IBOutlet NSPanel *theSheet; } @property (assign) IBOutlet NSWindow *window; @end AppDelegate.m #import “AppDelegate.h” @implementation AppDelegate @synthesize window = _window; – (IBAction) showTheSheet:(id)sender { [NSApp beginSheet:theSheet modalForWindow:(NSWindow *)_window modalDelegate:self didEndSelector:nil contextInfo:nil]; } … Read more
Just doing a bit of research… As I understand it, weak is similar to assign, in that they’re both weak references. However, assign does not create a zeroing reference. i.e. if the object in question is destroyed, and you access that property, you WILL get a BAD_ACCESS_EXCEPTION. Weak properties are automatically zeroed (= nil) when … Read more
To track growth of an application, Heapshot Analysis has proven very effective. It will capture both true leaks and accretion of memory where the allocations are not accounted for by leaks. You can see all of the retain/release events, and their backtrace, using the Allocations instrument. Hit the little (i) button on the Allocations instrument … Read more
You can use CFGetRetainCount with Objective-C objects, even under ARC: NSLog(@”Retain count is %ld”, CFGetRetainCount((__bridge CFTypeRef)myObject)); This is not particularly useful for debugging, though, for reasons amply described elsewhere. If you need to understand where an object is being retained and released, check out this answer for help using the Allocations instrument. The only case … Read more
Solution #1: Just remove the release statement. ARC will manage it for you. [imageArray release]; // remove this line ARC is Auto Reference Counting. As opposite to manual reference counting. There are a few great videos of talks from WWDC. I can provide the link if you wish to watch them. In Transitioning to ARC … Read more
From what I understand, although I can’t find a definitive source from Apple, unowned can be broken into two flavors, safe and unsafe. A bare unowned is unowned(safe): it is a specially wrapped reference which will throw an exception when a dealloced instance is referenced. The special case is unowned(unsafe): it is the Swift equivalent … Read more