how to chain methods in objective-c - objective-c

Question

I'm trying to implement a parsing method to turn an XML document into a multi-dimensional array, however it relies on needing to removal objects from an array just after adding that array to the multi-dimensional array, like so:
while (k<blockRowArray.count){ //loops through all rows one by one
NSLog(#"current k is %i", k);
GDataXMLDocument *currentRow = (GDataXMLDocument *) [blockRowArray objectAtIndex:k];
NSArray *arrayOfBlocks = [currentRow nodesForXPath:#"b" error:nil];
j = 0;
while (j <arrayOfBlocks.count) {
NSLog(#"current j is %i",j);
GDataXMLElement *blockElement = (GDataXMLElement *) [arrayOfBlocks objectAtIndex:j];
NSNumber* blockValue = [NSNumber numberWithInt:[[blockElement stringValue] intValue]];
[individualRowOfBlocks addObject:blockValue];
j++;
}
k++;
NSLog (#"Current row of blocks array is %#",individualRowOfBlocks);
[rowBlocks addObject:individualRowOfBlocks];
[individualRowOfBlocks removeAllObjects];
}
However [individualRowOfBlocks removeAllObjects] is clearly running at the same time or before [rowBlocks addObject:individualRowOfBlocks] as I end up with a multi-dimensional array with a set of empty arrays in it, so what I need to do is make sure that [individualRowOfBlocks removeAllObjects] runs after [individualRowOfBlocks removeAllObjects] any methods of doing this?

Answer 1

However [individualRowOfBlocks removeAllObjects] is clearly running at
the same time or before [rowBlocks addObject:individualRowOfBlocks] as
I end up with a multi-dimensional array with a set of empty arrays in
it, so what I need to do is make sure that [individualRowOfBlocks
removeAllObjects] runs after [individualRowOfBlocks removeAllObjects]
any methods of doing this?
Unless there are threads (or queues) involved, Objective-C methods are always going to be executed in the order written in the code unless the methods being called explicitly do stuff in threads/queues in their implementation (which is exceptionally unlikely in that code).
Every time you call [rowBlocks addObject:individualRowOfBlocks];, you are adding a new reference to the same individualRowOfBlocks array. If you subsequently change the contents of individualRowOfBlocks, every slot in rowBlocks will effectively reflect that change because every slot points to the same instance of the array.
It sounds like instead of removeAllObjects, you should create a new instance of NSMutableArray on each pass through the loop, assigning it to individualRowOfBlocks.