How to perform binary search on NSArray?

Question

What is the simplest way to do a binary search on an (already) sorted NSArray?

Some potential ways I have spotted so far include:

1. The use

Answer 1

The second option is definitely the simplest. Ole Begemann has a blog entry on how to use the NSArray's indexOfObject:inSortedRange:options:usingComparator: method:

NSArray *sortedArray = ... // must be sorted
id searchObject = ...
NSRange searchRange = NSMakeRange(0, [sortedArray count]);
NSUInteger findIndex = [sortedArray indexOfObject:searchObject 
                                inSortedRange:searchRange
                                      options:NSBinarySearchingFirstEqual
                              usingComparator:^(id obj1, id obj2)
                              {
                                  return [obj1 compare:obj2];
                              }];

See NSArray Binary Search