我的 UITableView 出现问题，删除该部分中的最后一行会导致应用程序终止并出现 NSInternalInconsistencyException：
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'
我的 UITableView 填充了来自 MPMediaItemCollection (self.detailCollection) 的 MPMediaItems。当最后一个被删除时，我想在空白单元格中显示“未找到结果”标签。
这是我的 cellForRowAtIndexPath：
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell...
if ([[self.detailCollection items] count] == 0) {
[tableView numberOfRowsInSection:1];
cell.textLabel.text = @"No results found";
//return cell;
} else {
MPMediaItem *song = (MPMediaItem *)[[self.detailCollection items] objectAtIndex:[indexPath row]];
if (song) {
cell.textLabel.text = [song valueForProperty:MPMediaItemPropertyTitle];
MPMediaItemArtwork *art = [song valueForProperty:MPMediaItemPropertyArtwork];
cell.imageView.image = [art imageWithSize:CGSizeMake(64, 64)];
}
}
return cell;
}
这是我删除行的代码：
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
PlaylistData *pData = [PlaylistData getInstance];
NSMutableArray *tempArray = [[self.eventDictionary valueForKey:[NSString stringWithFormat:@"%@", pData.selectedEvent]] mutableCopy];
NSMutableArray *newArray = [[NSMutableArray alloc] init];
if (editingStyle == UITableViewCellEditingStyleDelete) {
[tableView beginUpdates];
// Delete the row from the data source
[tempArray removeObjectAtIndex:indexPath.row];
[self.eventDictionary setValue:tempArray forKey:[NSString stringWithFormat:@"%@", pData.selectedEvent]];
[[NSUserDefaults standardUserDefaults] setValue:self.eventDictionary forKey:@"Playlist Items"];
[[NSUserDefaults standardUserDefaults] synchronize];
if ([tempArray count] == 0) {
[tableView numberOfRowsInSection:1];
}
for (int i=0; i<[tempArray count]; i++) {
NSString *pID = [NSString stringWithFormat:@"%@", [tempArray objectAtIndex:i]];
unsigned long long ullvalue = strtoull([pID UTF8String], NULL, 0);
NSNumber *UniqueID = [NSNumber numberWithUnsignedLongLong:ullvalue];
MPMediaQuery *cellQuery = [[MPMediaQuery alloc] init];
[cellQuery addFilterPredicate:[MPMediaPropertyPredicate predicateWithValue:UniqueID forProperty:MPMediaItemPropertyPersistentID]];
for (MPMediaItem *item in [cellQuery items]) {
[newArray addObject:item];
}
[cellQuery release];
}
if (![newArray count] == 0) {
self.detailCollection = [[MPMediaItemCollection alloc] initWithItems:newArray];
[tableView numberOfRowsInSection:[self.detailCollection count]];
} else {
[tableView numberOfRowsInSection:1];
[tableView reloadData];
}
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView endUpdates];
}
else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}
这是我的 numberOfRowsInSection：
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
if ([[self.detailCollection items] count] == 0 || [self.detailCollection items] == nil || [self.detailCollection items] == NULL) {
return 1;
}
return [[self.detailCollection items] count];
}
我的问题是：当 self.detailCollection == 0 时，为什么不创建“未找到结果”单元格？