//1 創(chuàng)建指定容量大小的可變數(shù)組對象  開始時候申請的內(nèi)存大小 可以根據(jù)以后情況進(jìn)行擴(kuò)展
        NSMutableArray *array = [[NSMutableArray alloc]initWithCapacity:20];

 //2 添加數(shù)組元素
        [array addObject:@"one"];
        NSLog(@"array = %@",array);

      //3 在指定下標(biāo)處 插入元素
        [array insertObject:@"two" atIndex:1];
        NSLog(@"array  =%@",array);

        //4 添加傳入數(shù)組的所有元素到數(shù)組中
        [array addObjectsFromArray:array];
         NSLog(@"array = %@",array);

        //5 刪除最后一個元素
        [array removeLastObject];
        NSLog(@"array = %@",array);

        //6  刪除指定位置
        [array removeObjectAtIndex:0];
         NSLog(@"array = %@",array);
        NSMutableArray * array1 = [NSMutableArray arrayWithObjects:@"one",@"two",@"three",@"four",@"five",@"one", nil];

        //7 刪除數(shù)組中所有出現(xiàn)的目標(biāo)元素
        [array1 removeObject:@"one"];
        NSLog(@"array1 = %@",array1);

       // 8  刪除某個范圍內(nèi) 目標(biāo)元素
        [array1 removeObject:@"one" inRange:NSMakeRange(4, 2)];
        NSLog(@"array1 = %@",array1);

        //9  刪除數(shù)組中某個范圍
        [array1 removeObjectsInRange:NSMakeRange(0, 3)];
        NSLog(@"array1 = %@",array1);
        //10 刪除 傳入輸出數(shù)組在數(shù)組中的元素
        [array1 removeObjectsInArray:array];
        NSLog(@"array1 = %@",array1);

        //11 刪除所有元素
        [array1 removeAllObjects];
        NSLog(@"array1 = %@",array1);

        //12 修改或重置數(shù)組
        [array setArray:array];
        NSLog(@"array = %@",array);

        //13 交換指定位置的元素
        [array1 exchangeObjectAtIndex:0 withObjectAtIndex:1];
        NSLog(@"array1 = %@",array1);

        //一個數(shù)組替換一個范圍
        [array1 replaceObjectsInRange:NSMakeRange(1, 2) withObjectsFromArray:@[@"ni",@"hao"]];
        NSLog(@"array1 = %@",array1);

        //使用傳入元素 替換某個下標(biāo)的元素
       [array1 replaceObjectAtIndex:1 withObject:@"one"];
        NSLog(@"array1 = %@",array1);
        

        //下標(biāo)集合
        NSMutableIndexSet *indexSet = [NSMutableIndexSet indexSetWithIndex:1];
        [indexSet addIndex:3];
        [indexSet addIndex:5];
        
        [array1 insertObjects:@[@"1",@"3",@"5"] atIndexes:indexSet];
        NSLog(@"array1 = %@",array1);
        
        [array1 removeObjectsAtIndexes:indexSet];
        NSLog(@"array1 = %@",array1);
        

注意：可變數(shù)組在for - in循環(huán)是不可以改變器內(nèi)部元素，如果要改變，用枚舉器

//將sectionTitles中數(shù)字字符串換成漢字字符串，按順序

NSDictionary *regionDicts = @{@"19764":@"美洲",@"20954":@"韓日",@"20691":@"香港",@"21062":@"臺灣",@"19774":@"中國",@"20681":@"歐洲"};
        NSMutableArray* sectionTitles = [NSMutableArray arrayWithObjects:@"20954",@"19764",@"20681",@"20691",@"21062",@"19774", nil];
        NSArray *regionAllKey = [regionDicts allKeys];
        
        for (NSString *regionKey in regionAllKey) {
            
            
            [sectionTitles enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
                if ([obj isEqualToString:regionKey]) {
                    *stop = YES;
                    if (*stop) {
                        [sectionTitles replaceObjectAtIndex:idx withObject:[regionDicts objectForKey:regionKey]];
                    }
               }
        }
        NSLog(@"調(diào)換后的sectionTitles = %@",sectionTitles);