Extra space in the end of string - objective-c

Question

I'm going through my array and find at which index the searched word is at. I use that information to put space between the words until i reach the next word. I save that text, and then store it in a variable.
I'm suspecting that my comparison between the lastObject and the arr objectAtIndex: i is not working, but i can't seem to figure out why?
NSArray *arr;
NSScanner *scanner = [NSScanner scannerWithString:_exerciseDocument];
while(![scanner isAtEnd])
{
NSString *buffer;
if([scanner scanCharactersFromSet:[NSCharacterSet whitespaceAndNewlineCharacterSet] intoString:&buffer])
{
[scanner scanUpToString:" " intoString:&buffer];
[scanner scanString:#" " intoString:nil];
}
else
{
}
for(int i=0; i <arr.count; i++)
{
NSString *stringToCheck = (NSString *)[arr objectAtIndex:i];
if([stringToCheck isEqualToString:#"Fokus:"])
{
_descriptionIndex = i;
}
if([stringToCheck isEqualToString:#"Niveau:"])
{
_focusIndex = i;
}
if([stringToCheck isEqualToString:#"Redskab:"])
{
_niveauIndex = i;
}
if([stringToCheck isEqualToString:#"Vanddybde:"])
{
_equipmentIndex = i;
}
}
_descriptiontToTextField = [[NSString alloc]init];
for(int i=1; i <_descriptionIndex; i++)
{
if(![[arr lastObject] isEqual:[arr objectAtIndex:i]])
{
_descriptiontToTextField = [_descriptiontToTextField stringByAppendingString:[ arr objectAtIndex:i]];
_descriptiontToTextField = [_descriptiontToTextField stringByAppendingString:#" "];
}
else
{
_descriptiontToTextField = [_descriptiontToTextField stringByAppendingString:[ arr objectAtIndex:i]];
}
}

Answer 1

First, -[NSString componentsSeparatedByCharactersInSet:] doesn't work the way you may think it does. If there are multiple spaces between words in _exerciseDocument, you're going to end up with a lot of empty strings in arr, which is not what you want. You may want to consider the use of a NSScanner (which, by default, skips whitespace and newline characters) to create your array.
Second, arr contains strings, and no other kind of objects. Given this, you should be using -[NSString isEqualToString:] instead for your comparisons.
Third, is there a reason you're starting your second loop at index 1 instead of index 0?

Answer 2

That if-statement never results to YES because your for-loop always terminates before reaching the last object in your array: i < _descriptionIndex.

Answer 3

i think you want to compare last object in array with all the objects inthe array, but isEqual is used to compare for two objects type not the values in the objects , as you can see
NSArray *arr = [_exerciseDocument componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
this will create arr as array of strings means all the objects are of type [NSString class]
if(![[arr lastObject] isEqual:[arr objectAtIndex:i]])
since all the objects are of same type isEqual will return true so your code will run in else part because of negation in if condition so use isEqualToString for comparing strings