.通过分类为数组添加一个倒序的一个方法. 比如: 数组中元素为 @”aa”, @”bb”, @”cc”, @”dd”, @”ee”, 倒序完之后为: @”ee”, @”dd”,@”cc”,@”bb

- (NSArray *)invertedOrder  

{
//1.先拷贝副本
    NSMutableArray *arr = [NSMutableArray arrayWithArray:self];
for (int i = 0; i < [arr count] / 2; i++) {
        [arr exchangeObjectAtIndex:i withObjectAtIndex:[arr count] - i - 1];
    }
return arr;
}
</span>

<span style="font-family:KaiTi_GB2312;font-size:24px;">NSArray *arr = @[@"aa",@"bb",@"cc",@"dd",@"ee"];   // 0 - 1
        NSArray *arr1 = [arr invertedOrder];
        NSLog(@"%@",arr1);</span>