Nsautoreleasepool Drain Error

is used to support Cocoa’s reference-counted memory management system. An autorelease pool stores objects that are sent a release message when the pool itself is drained.LanguageObjective-CSDKsiOS 2.0+macOS nsautoreleasepool is unavailable 10.0+tvOS 9.0+watchOS 2.0+On This PageOverviewSymbolsRelationshipsOverviewImportantIf you use Automatic Reference nsautoreleasepool vs @autoreleasepool Counting (ARC), you cannot use autorelease pools directly. Instead, you use @autoreleasepool blocks. For example,

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in place of:NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Code benefitting from a local autorelease pool. [pool release]; you would write:@autoreleasepool { // Code benefitting

Autorelease Pool Arc

from a local autorelease pool. } @autoreleasepool blocks are more efficient than using an instance of NSAutoreleasePool directly; you can also use them even if you do not use ARC.In a reference-counted environment (as opposed to one which uses garbage collection), an NSAutoreleasePool object contains objects that have received an autorelease pool objective c autorelease message and when drained it sends a release message to each of those objects. Thus, sending autorelease instead of release to an object extends the lifetime of that object at least until the pool itself is drained (it may be longer if the object is subsequently retained). An object can be put into the same pool several times, in which case it receives a release message for each time it was put into the pool. In a reference counted environment, Cocoa expects there to be an autorelease pool always available. If a pool is not available, autoreleased objects do not get released and you leak memory. In this situation, your program will typically log suitable warning messages.The Application Kit creates an autorelease pool on the main thread at the beginning of every cycle of the event loop, and drains it at the end, thereby releasing

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Us Learn more about Stack Overflow the company Business Learn more about hiring developers autorelease objective c or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack autorelease pool swift Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up How does the NSAutoreleasePool autorelease pool work? https://developer.apple.com/reference/foundation/nsautoreleasepool up vote 89 down vote favorite 32 As I understand it, anything created with an alloc, new, or copy needs to be manually released. For example: int main(void) { NSString *string; string = [[NSString alloc] init]; /* use the string */ [string release]; } My question, though, is wouldn't this be just as valid?: int main(void) { NSAutoreleasePool *pool; pool = [[NSAutoreleasePool alloc] init]; NSString *string; http://stackoverflow.com/questions/65427/how-does-the-nsautoreleasepool-autorelease-pool-work string = [[[NSString alloc] init] autorelease]; /* use the string */ [pool drain]; } objective-c memory-management nsautoreleasepool foundationkit share|improve this question edited Jun 6 at 19:18 community wiki 15 revs, 9 users 100%James Sumners add a comment| 9 Answers 9 active oldest votes up vote 64 down vote accepted Yes, your second code snippit is perfectly valid. Every time -autorelease is sent to an object, it is added to the inner-most autorelease pool. When the pool is drained, it simply sends -release to all the objects in the pool. Autorelease pools are simply a convenience that allows you to defer sending -release until "later". That "later" can happen in several places, but the most common in Cocoa GUI apps is at the end of the current run loop cycle. share|improve this answer edited Dec 29 '11 at 5:29 chakrit 40.1k18104145 answered Sep 15 '08 at 18:36 kperryua 8,77812822 5 where's the end of the current run loop cycle, if I don't have an loop? –Thanks Apr 13 '09 at 7:23 23 Shouldn't "outer-most" be "inner-most"? –Mike Weller Jun 8 '10 at 15:33 an object should be an object that is a subclass of NSObjec

here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings http://stackoverflow.com/questions/10400288/is-this-the-right-way-to-use-nsautoreleasepool and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation http://cocoasamurai.blogspot.com/2010/12/objective-c-memory-management-garbage.html Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it autorelease pool only takes a minute: Sign up Is this the right way to use NSAutoreleasePool? up vote 1 down vote favorite I'm new to Objective-C and I'm not sure if I'm using NSAutoreleasePool the right way. If I want to use autorelease only one time I use: NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSString *newText = [NSString stringWithFormat:@"%d", prograssAsInt]; sliderLabel.text = newText; nsautoreleasepool drain error [pool release]; //newText will be released If I want to use autorelease several times I use: NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSString *newText = [NSString stringWithFormat:@"%d", prograssAsInt]; sliderLabel.text = newText; [pool drain]; //newText will be released newText = [NSString stringWithFormat:@"%d", prograssAsInt]; sliderLabel.text = newText; [pool drain]; //newText will be released newText = [NSString stringWithFormat:@"%d", prograssAsInt]; sliderLabel.text = newText; [pool release]; //newText will be released Is this OK? Are there any memory leaks? objective-c ios memory-management autorelease share|improve this question edited May 1 '12 at 17:34 Chuck 175k19230340 asked May 1 '12 at 15:50 EOG 699823 add a comment| 4 Answers 4 active oldest votes up vote 3 down vote accepted (2) is not OK. -drain and -release are equivalent (in a ref-counting environment), and aftering -draining the autorelease pool is deallocated. So you will double-release the autorelease pool object and crash the program. Even before ARC, unless you are working in a very tight memory budget, it's atypical to create an NSAutoreleasePool besides the boilerplate main(). The objects -autoreleased into the pool will be released after every tick

is something i've seen new people to Cocoa & Objective-C mess up in ways I could just not conceive of on my own. In reality Objective-C memory management is not that hard. You simply need to be aware of some rules and follow a couple of good development practices. Good memory management practices are a good thing to follow on any platform. You don't want to be known as "that" app that hogs lots of memory, I have switched to alternative apps a couple times because the apps I was using were fine, but consumed far too much memory. Especially on iOS you need to follow good memory practices, because otherwise you'll be struggling to deal with low memory alerts and the possibility of your app being killed by iOS. Objective-C Retain CountObjective-C in retain count mode (not using garbage collection) is a simple idea. When you explicitly allocate an object it gets a retain count of 1 and when you call release or autorelease on an object it's retain count gets decremented and then the object will be collected. It is the only mode available on iOS Devices and has been in use on Mac OS X since the beginning of the OS. NSObject *object = [[NSObject aloc] init]; //retain count 1 [object release]; //retain count 0 When a object gets released -dealloc gets called on an object and its memory will be reclaimed. It's important to note that you never call dealloc on an object directly. In fact in all my time as a Cocoa Developer I've heard only 1 legitimate use of calling -dealloc on an object directly, I won't say what it is, but needless to say you would have a lot of Cocoa/Objective-C experience behind you before you would even conceive of doing this. In the same area as -release there is also -autorelease. -autorelease is the same as -release except that it'll perform the release in the future. This works great because with this an object you know you need to release in the future can be taken care of at the beginning of a method or section of code. -(void)doFoo:(BendingUnit *)bender { if(flexo) [flexo autorelease]; //will be sent release later ... Owning an Object In all these cases when we explicitly perform an -alloc we "own" the object, and when we call -release or -autorelease we relinquish ownership. If you call a method whose name contains 'alloc','new' or 'copy' or if you send a retain message to an object you now own the object and it is your responsibility to send it a -release or -autorelease at an appropriate time.