automatic-ref-counting - w3toppers.com

Do capture lists of inner closures need to redeclare `self` as `weak` or `unowned`?

The [weak self] in anotherFunctionWithTrailingClosure is not needed. You can empirically test this: class Experiment { func someFunctionWithTrailingClosure(closure: @escaping () -> Void) { print(“starting”, #function) DispatchQueue.main.asyncAfter(deadline: .now() + 1) { closure() print(“finishing”, #function) } } func anotherFunctionWithTrailingClosure(closure: @escaping () -> Void) { print(“starting”, #function) DispatchQueue.main.asyncAfter(deadline: .now() + 1) { closure() print(“finishing”, #function) } } func … Read more

Referring to weak self inside a nested block

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

Xcode ARC (automatic reference counting), “release is unavailable”

The two options given by NJones are valid and effective ways of dealing with ARC incompatibility. However, you do have a third option. Disabling ARC for specific files. Giving the flags -fno-objc-arc to your non ARC compatible compile sources affectively marks them as such upon compilation. You can find your compile sources under Targets → … Read more

SFHFKeychainUtils. iOS keychain. ARC compatible

here is the ARC compatible SFHFKeychainUtils, SFHFKeychainUtils.h // // SFHFKeychainUtils.h // // Created by Buzz Andersen on 10/20/08. // Based partly on code by Jonathan Wight, Jon Crosby, and Mike Malone. // Copyright 2008 Sci-Fi Hi-Fi. All rights reserved. // // Permission is hereby granted, free of charge, to any person // obtaining a copy … Read more

fake va_list in ARC

EDIT: This no longer works. As foreseen in the initial answer, the ABI appears to have changed out from under this answer Played around for a bit and got it to work — Double checked for leaks or abandoned memory and didn’t see any. NSArray *fixedArguments = [[NSArray alloc] initWithObjects: @”foo”, @”bar”, @”baz”, nil]; NSRange … Read more

-[Not A Type retain]: message sent to deallocated instance

This bridged cast may not work, as hatfinch describes in his answer here, because the CGColorRef returned from -CGColor may not hang around after your last reference to the UIColor that generates it. I thought this was a bug, based on the discussion in this Apple developer forum thread, but it was a misreading of … Read more

Why can’t I release an object anymore? [duplicate]

You need to turn off Automatic Reference Counting. You do this by clicking on your project in the navigator (the top item in the finder-like thing on the left), then click on your target, select “Build Settings” and turn off the option “Objective-C Automatic Reference Counting” (you can use the search field on the upper … Read more

ARC, Blocks and Retain Cycles

Assuming progress guarantees, a retain cycle might be exactly what you want. You explicitly break the retain cycle at the end of the block, so it’s not a permanent retain cycle: when the block is called, the cycle is broken. If you have something else keeping the operation around, though, you can store a reference … Read more

Do we need to use __weak self inside UIAnimationBlocks in ARC?

This is not a retain cycle. A retain cycle would be self -> block -> self In this case we have animation framework -> block block -> self where the first retain is only temporary – the block gets released when the animation ends. Even if a retain cycle happens, it will be only temporary … Read more

Why do weak NSString properties not get released in iOS?

NSString uses all sorts of internal trickery to reuse objects and avoid unnecessary allocations and copies. It can do this because NSString instances are immutable. In this case there is probably a shared instance to represent an empty string which is being returned by [[NSString alloc] init], and this shared instance will be retained somewhere … Read more