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我的应用程序有一个UITableViewController,它有一个表示城市名称的单元格列表。当用户单击一个单元格时,应用程序会将单元格accessoryType更改为UITableViewCellAccessoryCheckmark,并将单元格(城市名称)的文本值保存到持久存储区中。但是,我发现每次单击单元格时,都需要至少10秒才能将数据实际存储到持久存储区中。任何想法为什么发生这种情况而不是立即保存数据,为什么需要很长时间才能坚持下去?NSManagedContext需要很长时间来坚持
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cityName = [self.citySettingModel nameOfCityAtIndex:indexPath.row OfCountryAtIndex:self.countryIndex];
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
if (cell.accessoryType == UITableViewCellAccessoryCheckmark) {
cell.accessoryType = UITableViewCellAccessoryNone;
[[self.citySettingModel worldbikesCoreService] removeCity:cityName];
}
else {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
[[self.citySettingModel worldbikesCoreService] addCity:cityName toCountry:self.countryName];
}
}
用于创建一个城市和乡村的对象是不同的类
- (City *) addCity:(NSString*) cityName toCountry:(NSString*) countryName
{
NSManagedObjectContext *context = [self.delegate managedObjectContext];
Country *country = [self.countryDAO addCountry:countryName inManagedObjectContext:context];
City *city = [self.cityDAO addCity:cityName inManagedObjectContext:context];
[country addCitiesObject:city];
return city;
}
- (City*) addCity:(NSString*) cityName inManagedObjectContext:(NSManagedObjectContext *)context
{
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"City"];
fetchRequest.predicate = [NSPredicate predicateWithFormat:@"cityName = %@", cityName];
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"cityName" ascending:YES];
fetchRequest.sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSError *error;
NSArray *matches = [context executeFetchRequest:fetchRequest error:&error];
if (error) NSLog(@"error when retrieving city entities %@", error);
City *city;
if (!matches || [matches count] > 1) ;
else if ([matches count] == 0) {
city = [NSEntityDescription insertNewObjectForEntityForName:@"City" inManagedObjectContext:context];
city.cityName = cityName;
}
else city = [matches lastObject];
return city;
}
第一:你实际上在上面的代码中保存了上下文吗?我在这里看不到任何储蓄。第二:你不认为你的fetchrequest在addCity中:......可能对这10秒钟负责......? – codeclash 2012-04-14 01:12:22