A category method for NSArray that facilitates enumeration with regular draining of the autorelease pool. Useful for those long, memory accumulating loops.

gistfile1.m

@implementation NSArray (AutoreleasePoolDraining)

-(void)enumerateObjectsDrainingEveryIterations:(NSUInteger)iterationsBetweenDrains usingBlock:(void (^)(id object, NSUInteger index, BOOL *stop))block
{
    NSUInteger total = 0;
    NSUInteger count = self.count;
    NSUInteger numberOfChunks = (count / MAX(1,iterationsBetweenDrains) + 1);
    BOOL stop = NO;
    for ( NSUInteger chunk = 0; chunk < numberOfChunks; chunk++ ) {
        @autoreleasepool {
            for ( NSUInteger i = chunk*iterationsBetweenDrains; i < MIN(count, (chunk+1)*iterationsBetweenDrains); i++ ) {
                id object = self[i];
                block(object, total, &stop);
                if ( stop ) break;
                total++;
            }
        }
        if ( stop ) break;
    }
}

@end