我正在尝试将每个月的表视图分为多个部分。我开始使用苹果的DateSectionTitles示例。首先,我在核心数据库中添加了“sectionIdentifier”属性。然后在我的managedobject子类中添加了此方法。
- (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;
}
这就是我在titleForHeaderSection中所做的
- (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;
}
对于我的rowsInSection数,我执行此操作。
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?
提前致谢!
出了什么问题
首先,它不会在NSLog(@“tmp:%@”,tmp)中打印我的日志;
而且我得到以下错误:
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)'
最佳答案
人们通常忘记为nsmanagedobject的瞬态属性编码的一个常见错误是,人们忘记了也要在数据模型文件(xcdatamodeld)中“启用”瞬态属性。
关于iphone - 使用fetchedresultscontroller为每个月设置不同的部分,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/12815093/