nsautoreleasepool

On iOS/CocoaTouch I often see code that creates a new instance of NSAutoreleasePool within a method. I recently saw one within an NSOperation. What are the ground rules for setting up a new instance of NSAutoreleasePool? Why is this preferable to simply relying on the pre-existing release pool created in main.m? Thanks, Doug You can use a new autorelease pool whenever you want, but it is not always beneficial. It is required whenever you start a new thread or objects autoreleased in that thread will be leaked. It is also common to create new autorelease pools in a method where you create and

By my understanding, when an object is sent an autorelease message, if no autorelease pools exist other than the one in main.m , the object gets placed in the one in main.m . Assuming this is correct, I have a couple of questions: 1) Do all autoreleased objects stay in that pool until the termination of the app? 2) If 1 is true, does creating an autoreleased object without a local autorelease pool (therefore placing that object in the main.m pool) keep that object in memory until termination of the app or a memory warning is received? 3) When is the main.m autorelease pool drained, other than

I am getting this error message in the console: *** _NSAutoreleaseNoPool(): Object 0x10d2e0 of class NSPathStore2 autoreleased with no pool in place - just leaking I can't figure out what is the error? Thanks. This is a classic memory management issue, you are autoreleasing some objects without having an autorelease pool in place. Autoreleasing is not a magic. There is an object of type NSAutoreleasePool that keeps track of all objects you autorelease and ‘from time to time’ releases them: NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // An autoreleased object referenced by our

I was reading the documentation from apple about memory management when I got to autorelease pool blocks and something got me thinking. Any object sent an autorelease message inside the autorelease pool block is released at the end of the block. I am not sure I fully understand this. Any object created inside an autorelease pool block gets released at the end of the block anyway because that is it's life span. Why would you need to call autorelease to the object when it is going to get released anyway when it reaches the end of the block? To be clearer, I will give an example, of what I am

In Swift, I notice there is no @autoreleasepool{} construct, although Swift does use ARC. What is the proper way to manage an autoreleasepool in Swift, or has it been removed for some reason? This is explained in detail in WWDC 2014 session video number 418 "Improving Your App with Instruments", which you can also download as a PDF. But in short, the syntax is: autoreleasepool { /* code */ } Just FYI, Xcode constructed the full code as follows: autoreleasepool({ () -> () in // code }) Guess the parentheses identifies the functions closure. There is! It's just not really mentioned anywhere.

My project is in XCode 4.2. This project compiles for a regular debug build. But when I change the build type to profile (I want to profile memory usage), I get the error from this objective-c++ c++ class: /Volumes/mchinen/scm/Voicer/FilterAudioMixer.mm:53: error: stray '@' in program /Volumes/mchinen/scm/Voicer/FilterAudioMixer.mm: In member function 'void FilterAudioMixer::WriteToBuffer(SInt16*, int)': /Volumes/mchinen/scm/Voicer/FilterAudioMixer.mm:53: error: 'autoreleasepool' was not declared in this scope /Volumes/mchinen/scm/Voicer/FilterAudioMixer.mm:53: error: expected ;' before '{'

With instruments i got a memory leak on this piece of code and i don't understand why! -(void)goToThisUrl:(id) targetUrl { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; if (someCondition) { // Doing some stuff here } // Instruments show memory leak on data else { NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString: targetUrl]]; myTargetImage = [UIImage imageWithData:data]; // When releasing data(because data retainCount = 2), i got: // Incorrect decrement of the reference count of an object that is not owned at this point by the caller //[data release]; } [pool