How can I get an array of the indexes from another array that has been sorted?

You can also use below of the code, May its useful to you, NSSortDescriptor *_lastDescriptor = [[NSSortDescriptor alloc] initWithKey:@"" ascending:YES]; NSArray *_lastArray = [NSArray arrayWithObject:_lastDescriptor]; firstCharacterArray = (NSMutableArray *)[[nameIndexesDictionary allKeys] sortedArrayUsingDescriptors:_lastArray]; //firstCharacterArray = (NSMutableArray *)[[nameIndexesDictionary allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)]; for (NSString *eachlastIndex in firstCharacterArray) { NSSortDescriptor *lastDescriptor = [[NSSortDescriptor alloc] initWithKey:@"" ascending:YES]; //selector:@selector(localizedCaseInsensitiveCompare:)] ; NSArray *descriptorslast = [NSArray arrayWithObject:lastDescriptor]; [[nameIndexesDictionary objectForKey:eachlastIndex] sortUsingDescriptors:descriptorslast]; [lastDescriptor release]; }

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Here's what I ended up doing: //Create a mutable array of the indexes in the myArray (just a list from 0...n) NSMutableArray *indexes = [[NSMutableArray alloc] init]; for (int i = 0; i < myArray.count; i++){ [indexes addObject: [NSNumber numberWithInteger:i]]; } //Create a dictionary with myArray as the objects and the indexes as the keys NSDictionary *tempDictionary = [NSDictionary dictionaryWithObjects:myArray forKeys:indexes]; //Create an array of myArray's keys, in the order they would be in if they were sorted by the values NSArray *sorted = [tempDictionary keysSortedByValueUsingSelector: @selector(compare:)];