如何在一个已排序的NSArray中搜索某一特定字符串？答案是使用CFArray自带的搜索功能：

 
NSMutableArray *sortedArray = [NSMutableArray arrayWithObjects: @"Alice", @"Beth", @"Carol",@"Ellen",nil];
 
//Where is "Beth"?
unsigned index = (unsigned)CFArrayBSearchValues((CFArrayRef)sortedArray,
                                                                                    CFRangeMake(0, CFArrayGetCount((CFArrayRef)sortedArray)),
                                                                                    (CFStringRef)@"Beth",
                                                                                    (CFComparatorFunction)CFStringCompare,
                                                                                    NULL);
if (index < [sortedArray count])
{
         NSLog(@"Beth was found at index %u", index);
} else {
         NSLog(@"Beth was not found (index is beyond the bounds of sortedArray)");
}
 
//Where should we insert "Debra"?
unsigned insertIndex = (unsigned)CFArrayBSearchValues((CFArrayRef)sortedArray,
                                                                                            CFRangeMake(0, CFArrayGetCount((CFArrayRef)sortedArray)),
                                                                                            (CFStringRef)@"Debra",
                                                                                            (CFComparatorFunction)CFStringCompare,
                                                                                            NULL);
[sortedArray insertObject:@"Debra" atIndex:insertIndex];
NSLog([sortedArray description]);