我正在为我的公司编写一个小型iPhone应用程序，每次为每位员工提供一周的预订。我正在使用核心数据来获取给定周的“预订”列表，并希望将它们显示在UITableView中，分解为一周中每天的一个部分。
问题在于我需要在一周中的每一天显示7个部分（显示“没有预订”单元格，其中部分/日期没有预订）。
我有一个应用程序截图here（抱歉无法发布图片，因为我是StackOverlow的新手）
目前我正在通过使用'fetchResults'方法实现这一目标，该方法获取预订并将其组织到可能日期的数组中：
- (void)refetchResults {
// Drop bookings Array, replacing with new empty one
// 7 slots for 7 days each holding mutable array to recieve bookings where appropraite
self.bookings = [NSArray arrayWithObjects:[NSMutableArray array],
[NSMutableArray array], [NSMutableArray array],
[NSMutableArray array], [NSMutableArray array],
[NSMutableArray array], [NSMutableArray array], nil];
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Booking" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Limit to this weeks data
[fetchRequest setPredicate:
[NSPredicate predicateWithFormat:@"(date >= %@) && (date <= %@) && (resource == %@)",
firstDate,lastDate,resourceId]];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"recId" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, sortDescriptor2, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Fetch records in to array
NSError *error;
NSArray *results = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (results == nil) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
[fetchRequest release];
[sortDescriptor release];
[sortDescriptor2 release];
[sortDescriptors release];
// Walk through records and place in bookings Array as required
for (Booking *item in results) {
// Decide on array index by difference in firstDate and booking date
int idx = (int)[[item date] timeIntervalSinceDate:firstDate]/86400;
// Add the item to the approp MutArray
[(NSMutableArray *)[bookings objectAtIndex:idx] addObject:item];
}
// Reload table
[tableView reloadData];
}
我的问题是：有没有办法使用NSFetchedResultsController实现相同的结果？不知怎的，我需要让NSFetchedResultsController有7个部分，一个星期一天，其中一些可能没有预订。
任何帮助非常感谢：）
答案 0 :(得分：7)
所以，由于外面的天气不是很好，我已经开始回答我自己的问题并实施我对westsider的回复中描述的“解决方法”。
这个想法是保存一个'mapping'数组（只是一个简单的7槽int数组），它将mapview要求的部分映射到底层的fetchedresultscontroller部分。每个数组槽都有适当的部分索引或'-1'，其中没有底层部分（并且应该显示'No Booking'单元格）。
因此，我的refetchResults方法变为：
- (void)refetchResults {
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Booking" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Limit to this weeks data
[fetchRequest setPredicate:
[NSPredicate predicateWithFormat:@"(date >= %@) && (date <= %@) && (resource == %@)",
firstDate,lastDate,resourceId]];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"recId" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, sortDescriptor2, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Set up FRC
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:@"date" cacheName:nil];
self.fetchedResultsController = aFetchedResultsController;
self.fetchedResultsController.delegate = self;
[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor release];
[sortDescriptor2 release];
[sortDescriptors release];
// Run up FRC
NSError *error = nil;
if (![fetchedResultsController_ performFetch:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
// Update FRC map
[self updateFRCMap];
// Reload table
[tableView reloadData];
}
映射在以下方法中设置。只要需要刷新映射，就会调用此方法 - 例如，当我从fetchedresultscontroller获取已添加/删除/等的项目的回调时。
- (void)updateFRCMap {
// Set mapping table for seven days of week to appropriate section in frc
for (int idx=0;idx<7;idx++) { frcMap[idx] = -1; } // Reset mappings
// For each section
for (int sidx=0; sidx<[[self.fetchedResultsController sections] count]; sidx++)
{
// If section has items
if ([[[self.fetchedResultsController sections] objectAtIndex:sidx] numberOfObjects] > 0)
{
// Look at first booking of section to get date
NSDate *date = [(Booking *)[self.fetchedResultsController objectAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:sidx]] date];
// Decide on array index by difference in firstDate and booking date
int idx = (int)[date timeIntervalSinceDate:firstDate]/86400;
// Set map
frcMap[idx] = sidx;
}
}
}
这可能会稍微优化一下，但现在可以正常工作。我怀疑它可能会遭遇GMT / BST时钟更换问题需要修复...而不是时钟更改问题都是紧急的，呃Apple？ ; P
之后，只是在响应tableview时使用映射数组的情况：
#pragma mark -
#pragma mark Table view data source
// Gets the booking from the fetchedResultsController using a remapped indexPath
- (Booking *)bookingForMappedIndexPath:(NSIndexPath *)indexPath {
return (Booking *)[self.fetchedResultsController objectAtIndexPath:
[NSIndexPath indexPathForRow:indexPath.row inSection:frcMap[indexPath.section]]];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 7; // 7 days viewed
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Rows in section or 1 if no section
if (frcMap[section] != -1) {
id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:frcMap[section]];
return [sectionInfo numberOfObjects];
} else {
return 1;
}
}
- (UITableViewCell *)tableView:(UITableView *)_tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"RegularCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell.
[self configureCell:cell atIndexPath:indexPath];
return cell;
}
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath {
// If no actual bookings for section then its a blank cell
if (frcMap[indexPath.section] == -1) {
// Configure a blank cell.
cell.textLabel.text = @"No Bookings";
cell.detailTextLabel.text = @"";
cell.textLabel.font = [UIFont systemFontOfSize:16];
cell.textLabel.textColor = [UIColor lightGrayColor];
cell.accessoryType = UITableViewCellAccessoryNone;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
} else {
// Regular cell
Booking *booking = [self bookingForMappedIndexPath:indexPath];
cell.textLabel.text = booking.desc;
cell.detailTextLabel.text = [NSString stringWithFormat:@"%@ %@", booking.location, booking.detail];
cell.textLabel.font = [UIFont systemFontOfSize:14];
cell.textLabel.textColor = [UIColor darkTextColor];
cell.detailTextLabel.font = [UIFont systemFontOfSize:12];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
cell.selectionStyle = UITableViewCellSelectionStyleBlue;
}
}
非常欢迎任何评论或更好的写作方式：）
答案 1 :(得分：2)
我没有使用过这么多，但您可以查看NSFetchedResultsSectionInfo协议。它可以像这样使用，显然：
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSInteger numberOfRows = 0;
if ([[fetchedResultsController sections] count] > 0)
{
id <NSFetchedResultsSectionInfo> sectionInfo = [[fetchedResultsController sections] objectAtIndex:section];
numberOfRows = [sectionInfo numberOfObjects];
}
return numberOfRows;
}
答案 2 :(得分：1)
我也有这个问题。我编写了一个NSFetchedResultsController的子类来解决这个问题：
https://github.com/timothyarmes/TAFetchedResultsController
添