macOS Objective C - retain release problem

You have garbage collection on, so retrain/release are irrelevant. Also, don't use "new". Also, don't depend on retainCount for anything. Cocoa's memory management model depends on the concept of ownership. You own something, or you don't. If you don't own something, and you need to keep it around, you take ownership with retain. If you own something and you're done with it, you send it release to relinquish ownership. There are rules about what methods return objects you own and which return things you do not own. You should read:
http://developer.apple.com/library/...onceptual/MemoryMgmt/Articles/MemoryMgmt.html

If you want to use GC you can (but most don't), ARC is another option that handles the retaining and releasing for you. If you opt for those, no more retain/release. If you go manual, you need to learn the rules and abide by them.

-Lee

lee1210 said:

You have garbage collection on, so retrain/release are irrelevant. Also, don't use "new".

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Unless new has an specific issue with garbage collection, there is nothing wrong with using it. It is clear what it does, alloc, and then init, just like the longer form.

xStep said:

Unless new has an specific issue with garbage collection, there is nothing wrong with using it. It is clear what it does, alloc, and then init, just like the longer form.

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lee is right. Not because "new" doesn't work, but because it makes it harder to maintain code. When I want to know all the places where some object is allocated, I search for [SomeClass alloc]. Using a different method, which can only be used with one specific version of init, is not helpful at all.

gnasher729 said:

lee is right. Not because "new" doesn't work, but because it makes it harder to maintain code. When I want to know all the places where some object is allocated, I search for [SomeClass alloc]. Using a different method, which can only be used with one specific version of init, is not helpful at all.

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Alloc and new isn't the only way to get a retained object, so all your saying is that in those rare search instances you will reduce your search parameter list. I've never done that search.

quanganhct said:

Hello there,

...

I attached my code below, so please check it out.

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Don't use garbage collection. It's deprecated, and will become increasingly unsupported in the future. Use ARC instead.

Also, never call retainCount. It will only mislead you.

ARC all the way

Most people use ARC, which lets you largely avoid dealing with memory issues directly. It maintains the speed advantage of manual retain/release while simplifying the life of the programmer. I'm sure there's plenty of code out there that still uses retain/release manually, but I'd wager that new projects are mostly ARC.

So: do objective-c programmers use retain/release? A few do, but most do ARC these days.

-Lee

quanganhct said:

I've one more question. In real life, do objective-c programmers use release / retain in their codes ?

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In my experience (writing Objective-C code for a living):

1. Garbage collection is a pain in the **** and not worth the trouble. So you either use retain / release or ARC. One major application that used Garbage collection was Xcode itself and I think it caused a lot of trouble.

2. ARC requires that you use the 10.7 SDK or newer. If your code needs to run on 10.6, then you have to be careful. Running code on an earlier OS than your SDK means you need to know what you are doing. ARC on MacOS X requires 64 bit code. So your code with ARC won't run on a 2006 or possibly early 2007 Mac.

When you write new code in Objective-C, ARC is the way to go. If you have an old existing code base, with lots of old CoreFoundation code (not Objective-C) mixed in, the switch is a bit of work, but obviously you don't have the problem with new code.