【发布时间】：2013-12-13 12:18:18
【问题描述】：
我有一个包含 200,000 个项目的 JSON 对象。我需要遍历这些对象，并确定它们是否存在并执行相关操作（插入/更新/删除）。其外壳如下所示。当然，它实际上还没有保存任何东西。更多的是看看这条路需要多长时间。在 iPhone 4 上执行此操作大约需要 8 分钟，考虑到甚至还没有发生任何变化，这似乎很疯狂。
有没有更有效的方法来处理这个问题？
任何建议或指示将不胜感激。
- (void) progressiveInsert
{
prodAdd = 0;
prodUpdate = 0;
prodDelete = 0;
dispatch_queue_t backgroundDispatchQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
dispatch_async(backgroundDispatchQueue,
^{
_productDBCount = 0;
NSLog(@"Background Queue");
NSLog(@"Number of products in jsonArray: %lu", (unsigned long)[_products count]);
NSManagedObjectContext *backgroundThreadContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
[backgroundThreadContext setPersistentStoreCoordinator:_persistentStoreCoordinator];
[backgroundThreadContext setUndoManager:nil];
[fetchRequest setPredicate:predicate];
[fetchRequest setEntity:[NSEntityDescription entityForName:@"Products" inManagedObjectContext:_managedObjectContext]];
[fetchRequest setIncludesSubentities:NO]; //Omit subentities. Default is YES (i.e. include subentities)
[fetchRequest setFetchLimit:1];
[_products enumerateObjectsUsingBlock:^(id product, NSUInteger idx, BOOL *stop) {
predicate = [NSPredicate predicateWithFormat:@"code == %@", [product valueForKey:@"product_code"]];
[fetchRequest setPredicate:predicate];
NSError *err;
NSArray *fetchedObjects = [_managedObjectContext executeFetchRequest:fetchRequest error:&err];
if (fetchedObjects == nil) {
if ([[product valueForKey:@"delete"] isEqualToNumber:[NSNumber numberWithBool:TRUE]]){
prodDelete += 1;
} else {
prodAdd += 1;
}
} else {
if ([[product valueForKey:@"delete"] isEqualToNumber:[NSNumber numberWithBool:TRUE]]){
prodDelete += 1;
} else {
prodUpdate += 1;
}
}
dispatch_sync(dispatch_get_main_queue(), ^
{
self.productDBCount += 1;
float progress = ((float)self.productDBCount / (float)self.totalCount);
_downloadProgress.progress = progress;
if (_productDBCount == _totalCount){
NSLog(@"Finished processing");
_endProcessing = [NSDate date];
[_btn.titleLabel setText:@"Finish"];
NSLog(@"Processing time: %f", [_endProcessing timeIntervalSinceDate:_startProcessing]);
NSLog(@"Update: %i // Add: %i // Delete: %i", prodUpdate, prodAdd, prodDelete);
[self completeUpdateProcess];
}
});
}];
});
}
【问题讨论】：
-
batch insert 和 batch delete 的 Swift 示例