我有一些处理 CoreData 导入的 NSOperations 子类。我相信我已经勾选了大多数非主线程问题
main
我在方法中创建了自己的自动释放池NSManagedObjectContext
我为每个操作创建一个
这些操作被加载到一个 NSOperationQueue 中,最大并发操作数设置为 1。
该代码在 iOS 4.0.1 上完美运行,但在 iOS 3.1.3 设备上会收到大量日志消息,如下所示
*** _NSAutoreleaseNoPool(): Object 0x5f926c0 of class NSCFDictionary autoreleased with no pool in place - just leaking
NSOperation 子类主方法
-(void) main{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
@try {
//Start Operation
//====================================
NSManagedObjectID *objID = nil;
NSError *err = nil;
id user = nil;
if( !(userID = [self __lookup:[self userID] inContext: [self threadContext]]) ){
//Set the name of the element
user = [[self threadContext] objectWithID:objID];
//Update the name
[user setValue:@"John Doe" forKey:@"name"];
[user setValue:@"Hello world" forKey:@"status"];
}
if( ![[self threadContext] save:&err] ){
DebugLog(@"Couldn't savechanges %@", err);
}
//====================================
//End Operation
}
@catch (NSException * e) {
DebugLog(@"Exception %@",e);
}
//====================================
[pool drain];
}
__lookup:inContext:
方法_
-(NSManagedObjectID*) __lookup:(id)aID inContext:(NSManagedObjectContext*) aContext{
NSPredicate *predicate = nil;
NSEntityDescription *entity;
NSFetchRequest *fetchRequest = nil;
NSError *err = nil;
predicate = [NSPredicate predicateWithFormat:@"userID == %@",aID];
entity = [NSEntityDescription entityForName:@"User" inManagedObjectContext:aContext];
fetchRequest = [[[NSFetchRequest alloc] init] autorelease];
[fetchRequest setPredicate:predicate];
[fetchRequest setEntity:entity];
//Only fetch id's for speed
[fetchRequest setResultType:NSManagedObjectIDResultType];
return [[aContext executeFetchRequest:fetchRequest error:&err] lastObject];
}
大多数其他方法的实例方法,即threadContext
看起来与__lookup:inContext:
方法相似。我知道我不会为实例方法创建 Autorelease 池,但根据我对 autorelease 工作原理的理解,只要这些方法仅在 main 方法内部调用,在NSAutoreleasePool
创建之后,最外层池应该使用。我懒惰地创建诸如 NSManagedObjectContext 之类的对象,并且在大多数情况下不使用该start
方法