iOS NSMutableArray removeObjectAtIndex

Question

这是我在 ViewController.m 文件中的代码，

- (void)viewDidAppear:(BOOL)animated
 {
   [super viewDidAppear:animated];

   NSLog(@"%f",[self usedMemory]);
   NSMutableArray *array= [[NSMutableArray alloc]init];
   for (int i = 0; i < 100; i++) {
      NSMutableData *data = [NSMutableData dataWithLength:10000];
       [array addObject:data];
   }
   NSLog(@"%f",[self usedMemory]);

   for (int i = 0; i < 100; i++) {
       [array removeObjectAtIndex:0];
   }
   NSLog(@"%f",[self usedMemory]);
}

这是usedMemory方法:

- (double)usedMemory
{
    task_basic_info_data_t taskInfo;

    mach_msg_type_number_t infoCount = TASK_BASIC_INFO_COUNT;

    kern_return_t kernReturn = task_info(mach_task_self(),

                                     TASK_BASIC_INFO,

                                     (task_info_t)&taskInfo,

                                     &infoCount);
    if (kernReturn != KERN_SUCCESS

       )
    {
        return NSNotFound;
    }
    return taskInfo.resident_size / 1024.0 / 1024.0;
}

结果如下:

2015-01-26 22:39:00.058 audio_memory_test[9050:874963] 25.011719
2015-01-26 22:39:00.060 audio_memory_test[9050:874963] 26.312500
2015-01-26 22:39:00.060 audio_memory_test[9050:874963] 26.312500

为什么删除数组中的对象时内存没有释放？ removeObjectAtIndex 方法做了什么？如何释放这段内存？

Answer 1

当你在最后一个循环之后调用 [self usedMemory] 时，你的对象仍然保存在内存中。它们所属的自动释放池还没有被耗尽；这通常发生在您离开源代码的范围并且系统再次取得控制权时。