算法一
NSMutableArray *randSequence = [[NSMutableArray alloc] initWithCapacity:8];
for (int ii = 0; ii < 10; ++ii)
[randSequence addObject:[NSNumber numberWithInt:ii]];

for (int ii = 9; ii > -1; --ii) {
int r = arc4random() % 9
[randSequence exchangeObjectAtIndex:ii withObjectAtIndex:r];
}

算法二
@interface NSMutableArray (Shuffling)

• (void)shuffle;
  @end

// NSMutableArray_Shuffling.m

import "NSMutableArray_Shuffling.h"

@implementation NSMutableArray (Shuffling)

• (void)shuffle
  {
  NSUInteger count = [self count];
  for (NSUInteger i = 0; i < count; ++i) {
  // Select a random element between i and end of array to swap with.
  NSInteger nElements = count - i;
  NSInteger n = (arc4random() % nElements) + i;
  [self exchangeObjectAtIndex:i withObjectAtIndex:n];
  }
  }

@end