ios 自动排序（shuffle）密码键盘 实现算法

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