automatic-ref-counting

This is a relatively common design pattern: https://stackoverflow.com/a/17015041/743957 It allows you to return a subclass from your init calls. I'm trying to figure out the best method of achieving the same thing using Swift. I do know that it is very likely that there is a better method of achieving the same thing with Swift. However, my class is going to be initialized by an existing Obj-C library which I don't have control over. So it does need to work this way and be callable from Obj-C. Any pointers would be very much appreciated. I don't believe that this pattern can be directly

I wrote the following sample code to see how ARC works @property (nonatomic, weak) NSString *myString; @property (nonatomic, weak) NSObject *myObj; @end @implementation ViewController @synthesize myString = _myString; @synthesize myObj = _myObj; - (void) viewDidAppear:(BOOL)animated { NSLog(@"Appearing Obj: !%@!",self.myObj); NSLog(@"Appearing String: !%@!",self.myString); } - (void)viewDidLoad { self.myObj = [[NSObject alloc] init]; self.myString = [[NSString alloc] init]; NSLog(@"Loading Obj %@",self.myObj); NSLog(@"Loading String: !%@!",self.myString); } However surprisingly I got these

When compiling with ARC, method arguments often appear to be retained at the beginning of the method and released at the end. This retain/release pair seems superfluous, and contradicts the idea that ARC "produces the code you would have written anyway". Nobody in those dark, pre-ARC days performed an extra retain/release on all method arguments just to be on the safe side, did they? Consider: @interface Test : NSObject @end @implementation Test - (void)testARC:(NSString *)s { [s length]; // no extra retain/release here. } - (void)testARC2:(NSString *)s { // ARC inserts [s retain] [s length];

Can anyone help me remember what was the flag to tell the XCode to not use ARC for some file? I had several files in my project marked as such... Until I added another file and decided to convert that one to ARC. Sounds easy, right? I expected that I would be able to simply check a file that I want and let the XCode do it's magic. Well, not so easy, during pre-check it stripped all -Noarc flags from the files and now I need to manually re- apply the flag to several files. the moral of this story is: once your project is in ARC and you have some files marked as no ARC, do not re-run the convert

Suppose I already create a weak self using __weak typeof(self) weakSelf = self; [self doABlockOperation:^{ ... }]; Inside that block, if I nest another block: [weakSelf doAnotherBlockOperation:^{ [weakSelf doSomething]; } will it create a retain cycle? Do I need to create another weak reference to the weakSelf? __weak typeof(self) weakerSelf = weakSelf; [weakSelf doAnotherBlockOperation:^{ [weakerSelf doSomething]; } It depends. You only create a retain cycle if you actually store the block (because self points to the block, and block points to self ). If you don't intend to store either of

Can someone please explain to me the purpose of having __autoreleasing in the following sample code block? - (void)execute:(NSError * __autoreleasing *)error { // do stuff, possibly assigning error if something went wrong } I removed the __autoreleasing and everything still seems to compile/run fine. I started using obj-c post ARC so I never really learned/understood all those double underscore thingamajigs. I've read the ARC transition guide , but I don't fully understand their NSError example. Consider how ARC works with variables - each reference variable has a mode (implicit or explicit):