autorelease pools and release/retain

• in general, if you use the [filenames count;

int i;

for(i=0; i<[filenames count]; i++){
	NSString *fullPath = [NSString stringWithFormat:@"%@/%@", path, [filenames objectAtIndex:i]];
	[fullFilenames addObject:fullPath];
	// fullPath is 2, and will be released to 1 after removeAllObjects,
	// then autoreleased to 0 if not retained elsewhere
}

[gridView createGridItemViews:fullFilenames];

[fullFilenames removeAllObjects];
[fullFilenames release];

// the following method call releases the "filenames" array, and the "fullPath" objects
[aPool release];

… </code>

• objects have a retainCount, and when it reaches zero the object is deallocated from memory
• to find the retainCount you send the message to the object: (int)[object retainCount]
• to increment the retainCount, you send the message: [object retain]
• to decrement the retainCount, you send the message: [object release]

• adding an object to a mutable array increases the retain count by 1
• removing an object from a mutable array decreases the retain count by 1
• adding a view to another view (subview/superview) increases the retain count by 1
• removing or replacing a subview with another view decreases the retain count by 1
• if you need to keep an object around, you may need to use [object retain] before some of the methods that decrement the retain count