removing last node linked list in objective -c - objective-c

Question

I am trying to implement a removeLast function for a linked list in objective-c. My add function property works well because I can see the node I created, but when I try to remove a node it does not work. I have tried looking up general solutions for this, but have not come up with anything. Is there something special with objective-c that I should take a look at?
-(void) removeLast{
Node *newNode = [[Node alloc]init];
Node *tail = [[Node alloc]init];
if (self.head == NULL){
NSLog(#"No items to remove");
}
else{
newNode = self.head;
tail= self.head;
while (tail != NULL) {
tail = tail.next;
if (tail != NULL){
newNode = tail;
}
}
newNode.next = NULL;
}
}

Answer 1

I believe you've overcomplicated the algorithm. You don't need to keep a reference to the previous link if you always look one step ahead:
- (void) removeLast {
if (self.head == NULL) {
NSLog(#"Empty list");
} else if (self.head.next == NULL) {
self.head = NULL;
} else {
Node* current = self.head;
while (current.next.next != NULL)
current = current.next;
current.next = NULL;
}
}
This iterates through until it reaches the next-to-last node when current.next.next will be null. Then it makes that the last node.