NSAutoreleasePool is unavailable

问题

I am following "Programming in Objective-C" 3^rd edition and I am having problems with the first example.

I keep getting this error:

Semantic Issue: 'NSAutoreleasePool' is unavailable: not available in automatic reference counting mode

Here is my code:

//
// main.m
// prog1 //
// Created by Steve Kochan on 1/30/11.
// Copyright 2011 ClassroomM, Inc.. All rights reserved. //

#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSLog (@"Programming is fun!");
    [pool drain];
    return 0;
}

Any insight will be greatly appreciated.

回答1:

The compiler is being asked to compile the file with ARC (automatic reference counting) enabled. Turn that off or, better yet, modernize your example:

int main (int argc, const char * argv[]) {
    @autoreleasepool {
        NSLog (@"Programming is fun!");
    }
    return 0;
}

(No, I can't tell you how, specifically, to turn off ARC, if that was the route you were to go down due to the aforementioned NDA.)

回答2:

Quick post just in case you still looking

You can disable ARC in build settings.

Click on you project, in the left hand organizer.
Select your target, in the next column over.
Select the Build Settings tab at the top.
Scroll down to "Objective-C Automatic Reference Counting" (it may be listed as "CLANG_ENABLE_OBJC_ARC" under the User-Defined settings group), (if you do not find ARC option under build settings, you might need to toggle you compiler. You can find it under build settings)
and set it to NO.

回答3:

In my case, I wanted ARC on, and wanted to update a sample project to work properly. Apple's NSAutoReleasePool docs are technically correct, but don't come straight out and explain this. Here's how:

Take your application main, which probably looks something like this:

int main(int argc, char *argv[])
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    int retVal = UIApplicationMain(argc, argv, nil, NSStringFromClass([DemoAppDelegate class]));

    [pool release];

    return retVal;
}

And change it to look like this:

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([DemoAppDelegate class]));
    }
}

回答4:

Here is a link to Apple's transition guide to ARC.

OK...check this out. Specific change to NSAutoreleasePool - this is how Xcode initializes itself when you create your first app. I don't know about you, but I love this idea!

No worries if you are following along w/ Kochan's book. When starting your project, just uncheck the "Use ARC" box. Everything will work.

回答5:

ARC is enabled when you first create a new project. Right know the only way I know how to enable or not enable it is when you first create your program. It is one of the checkboxes you have to unselect.

来源：https://stackoverflow.com/questions/6655842/nsautoreleasepool-is-unavailable

标签

objective-c

nsautoreleasepool