学习笔记（一）

1.将数组内的元素逆序 ：

    NSMutableArray *array = [NSMutableArray arrayWithObjects:@"1",@"2",@"3",nil];
    NSArray* reversedArray = [[array reverseObjectEnumerator] allObjects];
    NSLog(@"reversedArray：%@", reversedArray); 

输出reversedArray：( 3, 2, 1)

2.在可变数组中插入一个数组

    NSArray *array1 = @[@"2", @"1"];
    NSMutableArray *array2 = [NSMutableArray arrayWithObjects:@"6",@"7", nil];
    /**
     *  @param 0      起始位置
     *  @param count 数组个数
     */
    NSRange range = NSMakeRange(0, [array1 count]);
    NSIndexSet *indexSet = [NSIndexSet indexSetWithIndexesInRange:range];
    [array2 insertObjects:array1 atIndexes:indexSet];
    NSLog(@"%@", array2); 

输出array2: (2,1,6,7)