Question

I am working on multi-threading using the following codes in XCode4:

#import <Foundation/Foundation.h>

bool trigger = false;
NSLock  *theLock=[NSLock new];

@interface Metronome : NSObject
+(void)tick:(id)param;
@end

@implementation Metronome
+(void)tick:(id)param{
while(1)
   {
           NSLog(@"TICK\n");
           usleep(1000000);
           [theLock lock];
           trigger = true;
           [theLock unlock];
   }
}
@end

int main()
{
    [NSThread detachNewThreadSelector:@selector(tick:)
toTarget:[Metronome class] withObject:nil];
}

There is no compiling error, but during execution the console pops up the following warning:

objc[688]: Object 0x100300ff0 of class NSThread autoreleased with no pool
in place - just leaking - break on objc_autoreleaseNoPool() to debug

I’m not familiar with the memory management of obj-C. Can someone explain this to me? Thanks a lot!

Answer 1

you have to create a NSAutoreleasePool for every thread that need invoke autorelease include main thread

int main()
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    [NSThread detachNewThreadSelector:@selector(tick:)
toTarget:[Metronome class] withObject:nil];
    [pool release];
}