使用NSFetchedResult控制器和每个月的节标题 [英] working with a NSFetchedResult controller and section headers for each month
问题描述
可能重复:
使用fetchedresultcontroller为每个月设置不同的部分
我试图将每个月的 UITableview 拆分成几个部分。我开始使用苹果的 DateSectionTitles 示例。首先,我在我的 coredata 中添加了一个属性sectionIdentifier。然后在我的 managedobject 子类中添加了此方法。
- (NSString *)sectionIdentifier {
//根据需要创建和缓存段标识符。
[self willAccessValueForKey:@sectionIdentifier];
NSString * tmp = [self primitiveSectionIdentifier];
[self didAccessValueForKey:@sectionIdentifier];
if(!tmp){
/ *
节按月和年组织。创建段标识符作为表示数字的字符串(年* 1000)+月;这样,他们将按照时间顺序正确地排序,而不管月份的实际名称。
* /
NSCalendar * calendar = [NSCalendar currentCalendar];
NSDateComponents * components = [日历组件:(NSYearCalendarUnit | NSMonthCalendarUnit)fromDate:[self date]];
tmp = [NSString stringWithFormat:@%d,([components year] * 1000)+ [components month]];
[self setPrimitiveSectionIdentifier:tmp];
}
NSLog(@tmp:%@,tmp);
return tmp;
}
这是我在我的titleForHeaderSection
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
id< NSFetchedResultsSectionInfo> theSection = [[self.fetchedResultsController sections] objectAtIndex:section];
/ *
节信息来自事件的sectionIdentifier,它是一个表示数字(年* 1000)+月的字符串。
要显示节标题,请将年份和月份组件转换为字符串表示形式。
* /
static NSArray * monthSymbols = nil;
if(!monthSymbols){
NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
[formatter setCalendar:[NSCalendar currentCalendar]];
monthSymbols = [formatter monthSymbols];
}
NSInteger numericSection = [[TheSection name] integerValue];
NSInteger year = numericSection / 1000;
NSInteger month = numericSection - (year * 1000);
NSString * titleString = [NSString stringWithFormat:@%@%d,[monthSymbols objectAtIndex:month-1],year];
NSLog(@titelstring is:%@,titleString);
return titleString;
}
对于我的行数InSection我这样做。
id< NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
NSInteger count = [sectionInfo numberOfObjects];
return count;
这是我的NumberOfSectionsInTableview
NSInteger count = [[self.fetchedResultsController sections] count];
return count;
有人可以帮忙吗?
提前!
发生了什么问题
打印我的日志NSLog(@tmp:%@,tmp);
并且我得到以下错误:
** CoreData **:error:(NSFetchedResultsController)段名键路径sectionIdentifier的nil值。对象将被放置在未命名的部分
2012-10-10 10:41:17.475 RacingGenk [15785:c07] ***由于未捕获异常NSRangeException终止应用程序,原因:' - [__ NSCFArray objectAtIndex:]:指数(-1(或可能更大))超出边界(12)'
这里是我设置我的NSFetchresultcontroller
- (void)getKalender //附加一个NSFetchRequest UITableViewController
{
NSFetchRequest * request = [NSFetchRequest fetchRequestWithEntityName:@Kalender];
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@dateascending:YES]];
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.genkDatabase.managedObjectContext
sectionNameKeyPath:@Kalender.sectionIdentifiercacheName:@Root] ;
self.fetchedResultsController.delegate = self;
self.fetchedResultsController = self.fetchedResultsController;
我认为必须
sectionNameKeyPath:@sectionIdentifier
而不是
sectionNameKeyPath:@Kalender.sectionIdentifier
pre>
构建已提取结果控制器。
Possible Duplicate:
Setting a different section for each month with fetchedresultcontrollerI am trying to split my UITableview into sections for each month. I start working with the DateSectionTitles example of apple. First of all I added in my coredata a attribute 'sectionIdentifier'. Then in my managedobject subclass I added this method.
- (NSString *)sectionIdentifier { // Create and cache the section identifier on demand. [self willAccessValueForKey:@"sectionIdentifier"]; NSString *tmp = [self primitiveSectionIdentifier]; [self didAccessValueForKey:@"sectionIdentifier"]; if (!tmp) { /* Sections are organized by month and year. Create the section identifier as a string representing the number (year * 1000) + month; this way they will be correctly ordered chronologically regardless of the actual name of the month. */ NSCalendar *calendar = [NSCalendar currentCalendar]; NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit) fromDate:[self date]]; tmp = [NSString stringWithFormat:@"%d", ([components year] * 1000) + [components month]]; [self setPrimitiveSectionIdentifier:tmp]; } NSLog(@"tmp: %@",tmp); return tmp; }
This is what i do in my titleForHeaderSection
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { id <NSFetchedResultsSectionInfo> theSection = [[self.fetchedResultsController sections] objectAtIndex:section]; /* Section information derives from an event's sectionIdentifier, which is a string representing the number (year * 1000) + month. To display the section title, convert the year and month components to a string representation. */ static NSArray *monthSymbols = nil; if (!monthSymbols) { NSDateFormatter *formatter = [[NSDateFormatter alloc] init]; [formatter setCalendar:[NSCalendar currentCalendar]]; monthSymbols = [formatter monthSymbols]; } NSInteger numericSection = [[theSection name] integerValue]; NSInteger year = numericSection / 1000; NSInteger month = numericSection - (year * 1000); NSString *titleString = [NSString stringWithFormat:@"%@ %d", [monthSymbols objectAtIndex:month-1], year]; NSLog(@"titelstring is: %@",titleString); return titleString; }
For my number of rowsInSection I do this.
id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section]; NSInteger count = [sectionInfo numberOfObjects]; return count;
And this for my NumberOfSectionsInTableview
NSInteger count = [[self.fetchedResultsController sections] count]; return count;
Can anybody help?
Thanks in advance!
What is going wrong
First off all it don't prints my log in NSLog(@"tmp: %@",tmp); And also I get the following error:
**CoreData**: error: (NSFetchedResultsController) A section returned nil value for section name key path 'sectionIdentifier'. Objects will be placed in unnamed section 2012-10-10 10:41:17.475 RacingGenk[15785:c07] *** Terminating app due to uncaught exception 'NSRangeException', reason: '-[__NSCFArray objectAtIndex:]: index (-1 (or possibly larger)) beyond bounds (12)'
EDIT Here is where I set my NSFetchresultcontroller
- (void)getKalender // attaches an NSFetchRequest to this UITableViewController { NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Kalender"]; request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"date" ascending:YES]]; self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:self.genkDatabase.managedObjectContext sectionNameKeyPath:@"Kalender.sectionIdentifier" cacheName:@"Root"]; self.fetchedResultsController.delegate = self; self.fetchedResultsController = self.fetchedResultsController;
解决方案I think it must be
sectionNameKeyPath:@"sectionIdentifier"
instead of
sectionNameKeyPath:@"Kalender.sectionIdentifier"
in the construction of the fetched results controller.
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