NSMutableArray用法

创建可变数组

NSMutableArray *array = [[NSMutableArray alloc] init];

 [array addObject:@"One"];

 [array addObject:@"Two"]; 

 [array addObject:@"Three"];

 [array removeObject:@"One"];//删除指定的元素。

 [array removeAllObjects];//删除所有元素

 [array removeLastObject];//删除最后一个元素

 [array removeObjectAtIndex:1];//删除指定索引的元素

 [array exchangeObjectAtIndex:0 withObjectAtIndex:2];//交换两个数组元素的位置

  NSString *str =@"I am a so bad man";

  NSArray *array = [str componentsSeparatedByString:@" "];//用空格来分割字符串，放到数组里

  NSMutableArray *mutableArr = [[NSMutableArray alloc] init];

  NSEnumerator *enumerator = [array reverseObjectEnumerator];

  NSString *obj;

  while (obj = [enumerator nextObject])

  {

     [mutableArr addObject:obj];

  }

  NSString *newStr = [mutableArr componentsJoinedByString:@" "];//从数组合并元素到字符串

   NSMutableArray *array = [NSMutableArray arrayWithObjects:@"1",@"3",@"2", nil];

   //替换指定索引的元素

   [array replaceObjectAtIndex:1 withObject:@"4"];

   NSLog(@"array = %@",array);

数组的内存管理

void arrayMemory()

{

    NSMutableArray *array = [NSMutableArray array];

    Student *stu1 = [Student studentWithAge:10];

    Student *stu2 = [Student studentWithAge:20];

    

   //对被添加元素做一次retain操作，计数器+1

    [array addObject:stu1];

    [array addObject:stu2];

    

   //对被删除的元素做一次release操作，计数器-1

    [array removeObject:stu1];

    

   //当数组被释放的时候，会对所有的元素都做一次release操作

}

数组排序

void arraySort()

{

    NSMutableArray *array = [NSMutableArray arrayWithObjects:@"1",@"3",@"2", nil];

    [array sortUsingSelector:@selector(compare:)];

    NSLog(@"array = %@",array);

}