How can I reverse a NSArray in Objective-C

Questions

I need to reverse my NSArray.

As an example:

[1,2,3,4,5] must become: [5,4,3,2,1]

What is the best way to achieve this?

Answers

@implementation NSArray (Reverse)

- (NSArray *)reversedArray {
    NSMutableArray *array = [NSMutableArray arrayWithCapacity:[self count]];
    NSEnumerator *enumerator = [self reverseObjectEnumerator];
    for (id element in enumerator) {
        [array addObject:element];
    }
    return array;
}

@end

@implementation NSMutableArray (Reverse)

- (void)reverse {
    if ([self count] <= 1)
        return;
    NSUInteger i = 0;
    NSUInteger j = [self count] - 1;
    while (i < j) {
        [self exchangeObjectAtIndex:i
                  withObjectAtIndex:j];

        i++;
        j--;
    }
}

@end

Source

License : cc by-sa 3.0

http://stackoverflow.com/questions/586370/how-can-i-reverse-a-nsarray-in-objective-c

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