Comments on: iPhone Programming Part 2 : Objective C Memory Management

By: links for 2009-09-04 | Alones world

links for 2009-09-04 | Alones world — Sat, 05 Sep 2009 01:49:37 +0000

[...] coders» Blog Archive » iPhone Programming Part 2 : Objective C Memory Management (tags: iphone_dev objectivec memory iphone retain) [...]

By: Shawn

Shawn — Tue, 23 Jun 2009 22:55:09 +0000

I found an answer to my question on StackOverflow… so for anyone that is interested:

You DO need to release it. See
“As it rebuilds the object hierarchy, however, UIKit reestablishes connections between the objects using the setValue:forKey: method, which uses the available setter method or retains the object by default if no setter method is available.” in Nib Object Retention

In other words, because you haven’t specified these entries as @property (which implicitly declares a setter), or provided a setter directly, there is no available setter method, and the final part of this paragraph applies – the object is retained by default.

By: Shawn

Shawn — Tue, 23 Jun 2009 22:49:51 +0000

What about an IBOutlet variable linked to an item in an Interface Builder nib? I didn’t think I was required to release them since I never explicitly created them with an alloc/init but I was seeing object allocations that were never released (and not reported by the Leaks tool) until I did.

By: Benoit Cerrina

Benoit Cerrina — Sun, 15 Mar 2009 15:25:44 +0000

One thing I do to help manage autorelease pool is I create a c++ object which wraps one, allocating the autorelease pool in its constructor and releasing it in its destructor. Then I can use instances of this object allocated on the stack to quickly create autorelease pools with a life time bounded by a given scope. It makes for much less errors in case where there are several ways to exit a scope (like a loop with breaks and continues or a function with multiple returns)

By: Karmen Blake

Karmen Blake — Fri, 13 Mar 2009 15:40:15 +0000

Great article. Examples help a lot.

By: iPhoneKicks.com

iPhoneKicks.com — Sat, 07 Mar 2009 15:59:15 +0000

iPhone Programming: Objective C Memory Management …

You’ve been kicked (a good thing) – Trackback from iPhoneKicks.com – iPhone SDK links, community driven…

By: aCoder

aCoder — Wed, 04 Mar 2009 11:52:21 +0000

Yes, that helps. Thank you hhamm.

By: hhamm

hhamm — Tue, 03 Mar 2009 18:31:21 +0000

the retain counter will be increased only if you call the retain method. The same for the release method to decrease the retain counter. But there are some automatical created retain / release calls. If you use the “@property (nonatomic, retain) NSObject * myVar;” for example. In this case if you assign a value by using its setter method (e.g. self.myVar = newValue or somewhere outside your class : object.myVar = newValue) there will be an autorelease message to the previous value of myVar and a retain message to the new value. Also there are retain calls hidden in Apples Library Objects, especially the Collection classes.
Like if you add an object to a Dictionary it will receive a retain and vice versa if you remove it an autorelease (same on other collection classes like NSArray, NSMutableArray, etc.)

To understand the behaviour of release, retain, autorelease and so on, it helped me to write a simple sandbox class and override these methods with a simple NSLog output to see when a retain or release was called.

hope that helps you out?

By: aCoder

aCoder — Tue, 03 Mar 2009 16:56:29 +0000

Is the retain counter of an object incremented when a new pointer point to it, or the retain method is required for the counter increment?