我目前正在努力解决我的应用程序的核心数据问题，该问题违背了(我的)逻辑。我确定我做错了什么，但看不到什么。
我正在我的核心数据实体上执行基本的 executeFetchRequest，但是返回的托管对象数组似乎永远不会被释放，只有当我在 iPhone 上运行它时，它在模拟器下完全按预期工作。
尽管使用了 NSAutoreleasePool 来确保最小化内存占用。我还检查了 Instruments，没有泄漏，只是不断增加内存分配(通过 '[NSManagedObject(_PFDynamicAccessorsAndPropertySupport) allocWithEntity:]')。在我的实际应用中，这最终会导致 didReceiveMemoryWarning 调用。
我制作了一个最小的程序来重现下面的问题。我尝试了各种方法，例如在排空池之前对所有对象进行故障处理，但没有任何乐趣。如果我提供一个指向获取的 NSError 指针，则不会返回任何错误。没有后台线程在运行。
#import <mach/mach.h>
#import <mach/mach_host.h>
+(natural_t) get_free_memory {
mach_port_t host_port;
mach_msg_type_number_t host_size;
vm_size_t pagesize;
host_port = mach_host_self();
host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
host_page_size(host_port, &pagesize);
vm_statistics_data_t vm_stat;
if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS) {
NSLog(@"Failed to fetch vm statistics");
return 0;
}
/* Stats in bytes */
natural_t mem_free = vm_stat.free_count * pagesize;
return mem_free;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Set up the edit and add buttons.
self.navigationItem.leftBarButtonItem = self.editButtonItem;
UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject)];
self.navigationItem.rightBarButtonItem = addButton;
[addButton release];
// Obtain the Managed Object Context
NSManagedObjectContext *context = [(id)[[UIApplication sharedApplication] delegate] managedObjectContext];
// Check the free memory before we start
NSLog(@"INITIAL FREEMEM: %d", [RootViewController get_free_memory]);
// Loop around a few times
for(int i=0; i<20; i++) {
// Create an autorelease pool just for this loop
NSAutoreleasePool *looppool = [[NSAutoreleasePool alloc] init];
// Check the free memory each time around the loop
NSLog(@"FREEMEM: %d", [RootViewController get_free_memory]);
// Create a minimal request
NSEntityDescription *entityDescription = [NSEntityDescription
entityForName:@"TestEntity" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDescription];
// Perform the fetch
NSArray *array = [context executeFetchRequest:request error:nil];
[request release];
// Drain the pool - should release the fetched managed objects?
[looppool drain];
}
// Check the free menory at the end
NSLog(@"FINAL FREEMEM: %d", [RootViewController get_free_memory]);
}
当我在模拟器上运行上面的代码时，我得到以下输出(对我来说这看起来很合理):
2011-06-06 09:50:28.123 renniksoft[937:207] INITIAL FREEMEM: 14782464
2011-06-06 09:50:28.128 renniksoft[937:207] FREEMEM: 14807040
2011-06-06 09:50:28.135 renniksoft[937:207] FREEMEM: 14831616
2011-06-06 09:50:28.139 renniksoft[937:207] FREEMEM: 14852096
2011-06-06 09:50:28.142 renniksoft[937:207] FREEMEM: 14872576
2011-06-06 09:50:28.146 renniksoft[937:207] FREEMEM: 14897152
2011-06-06 09:50:28.149 renniksoft[937:207] FREEMEM: 14917632
2011-06-06 09:50:28.153 renniksoft[937:207] FREEMEM: 14938112
2011-06-06 09:50:28.158 renniksoft[937:207] FREEMEM: 14962688
2011-06-06 09:50:28.161 renniksoft[937:207] FREEMEM: 14983168
2011-06-06 09:50:28.165 renniksoft[937:207] FREEMEM: 14741504
2011-06-06 09:50:28.168 renniksoft[937:207] FREEMEM: 14770176
2011-06-06 09:50:28.174 renniksoft[937:207] FREEMEM: 14790656
2011-06-06 09:50:28.177 renniksoft[937:207] FREEMEM: 14811136
2011-06-06 09:50:28.182 renniksoft[937:207] FREEMEM: 14831616
2011-06-06 09:50:28.186 renniksoft[937:207] FREEMEM: 14589952
2011-06-06 09:50:28.189 renniksoft[937:207] FREEMEM: 14610432
2011-06-06 09:50:28.192 renniksoft[937:207] FREEMEM: 14630912
2011-06-06 09:50:28.194 renniksoft[937:207] FREEMEM: 14651392
2011-06-06 09:50:28.197 renniksoft[937:207] FREEMEM: 14671872
2011-06-06 09:50:28.200 renniksoft[937:207] FREEMEM: 14692352
2011-06-06 09:50:28.203 renniksoft[937:207] FINAL FREEMEM: 14716928
但是，当我在实际的 iPhone 4 (4.3.3) 上运行它时，我得到以下结果:
2011-06-06 09:55:54.341 renniksoft[4727:707] INITIAL FREEMEM: 267927552
2011-06-06 09:55:54.348 renniksoft[4727:707] FREEMEM: 267952128
2011-06-06 09:55:54.702 renniksoft[4727:707] FREEMEM: 265818112
2011-06-06 09:55:55.214 renniksoft[4727:707] FREEMEM: 265355264
2011-06-06 09:55:55.714 renniksoft[4727:707] FREEMEM: 264892416
2011-06-06 09:55:56.215 renniksoft[4727:707] FREEMEM: 264441856
2011-06-06 09:55:56.713 renniksoft[4727:707] FREEMEM: 263979008
2011-06-06 09:55:57.226 renniksoft[4727:707] FREEMEM: 264089600
2011-06-06 09:55:57.721 renniksoft[4727:707] FREEMEM: 263630848
2011-06-06 09:55:58.226 renniksoft[4727:707] FREEMEM: 263168000
2011-06-06 09:55:58.726 renniksoft[4727:707] FREEMEM: 262705152
2011-06-06 09:55:59.242 renniksoft[4727:707] FREEMEM: 262852608
2011-06-06 09:55:59.737 renniksoft[4727:707] FREEMEM: 262389760
2011-06-06 09:56:00.243 renniksoft[4727:707] FREEMEM: 261931008
2011-06-06 09:56:00.751 renniksoft[4727:707] FREEMEM: 261992448
2011-06-06 09:56:01.280 renniksoft[4727:707] FREEMEM: 261574656
2011-06-06 09:56:01.774 renniksoft[4727:707] FREEMEM: 261148672
2011-06-06 09:56:02.290 renniksoft[4727:707] FREEMEM: 260755456
2011-06-06 09:56:02.820 renniksoft[4727:707] FREEMEM: 260837376
2011-06-06 09:56:03.334 renniksoft[4727:707] FREEMEM: 260395008
2011-06-06 09:56:03.825 renniksoft[4727:707] FREEMEM: 259932160
2011-06-06 09:56:04.346 renniksoft[4727:707] FINAL FREEMEM: 259555328
空闲内存的数量在每次循环中减少，与我获取的托管对象成比例，例如如果我获取两倍数量的对象，那么可用内存会以两倍的速度减少 - 所以我非常有信心未释放的是托管对象。
请注意，正在获取的实体非常基本，只有两个属性，一个字符串和一个 16 位整数。在上面的例子中有 1000 个被获取。我用来生成它们的代码如下:
// Create test entities
for(int i=0; i<1000; i++) {
id entity = [NSEntityDescription insertNewObjectForEntityForName:@"TestEntity" inManagedObjectContext:context];
[entity setValue:[NSString stringWithFormat:@"%d",i] forKey:@"name"];
[entity setValue:[NSNumber numberWithInt:i] forKey:@"value"];
}
if (![context save:nil]) {
NSLog(@"Couldn't save");
}
如果有人能向我解释发生了什么，我将不胜感激!这个问题是唯一一个阻碍我的应用程序发布的问题。它在模拟器上运行得很漂亮!!
如果我能提供更多信息，请告诉我。
最佳答案
呸!这就是我看起来很蠢的地方!
我将“NSZombieEnabled”设置为 YES，这意味着获取的数据没有被释放!没有它一切正常:-)
关于iPhone 核心数据 - 获取的托管对象未在设备上发布(在模拟器上很好)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6249840/