我有一个简单的 UITableView Controller ,用于显示 CoreData。我正在尝试实现 - (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath;并在动画方面遇到问题。核心数据存储已更新,但动画不起作用。
如何让动画正确反射(reflect)核心数据对象发生的变化?
例如:
初始订单:
第 2 项之后到顶部:
或者,初始订单:
将项目 1 移动到位置 3 后:
相关代码如下:
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
//this implementation is from this tutorial: http://www.cimgf.com/2010/06/05/re-ordering-nsfetchedresultscontroller/
NSMutableArray *things = [[fetchedResultsController fetchedObjects] mutableCopy];
// Grab the item we're moving.
NSManagedObject *thing = [fetchedResultsController objectAtIndexPath:fromIndexPath];
// Remove the object we're moving from the array.
[things removeObject:thing];
// Now re-insert it at the destination.
[things insertObject:thing atIndex:[toIndexPath row]];
// All of the objects are now in their correct order. Update each
// object's displayOrder field by iterating through the array.
int i = 0;
for (NSManagedObject *mo in things)
{
[mo setValue:[NSNumber numberWithInt:i++] forKey:@"order"];
}
NSLog(@"things: %@", things);
[things release], things = nil;
[managedObjectContext save:nil];
}
和代表:
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
NSLog(@"didChangeObject:");
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
NSLog(@"ResultsChangeInsert:");
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
最佳答案
该问题是由委托(delegate)干扰我的重新排序实现引起的。 我在保存 ManagedObjectContext 之前添加了一个 bool 值:
reordering = YES; [managedObjectContext save:nil];
并使用它跳过任何 FetchedResultsController Delegate 函数。不是最好的解决方案,但它适用于此实现。如果有任何评论/答案解释为什么会发生这种情况,我将不胜感激。
/**
Delegate methods of NSFetchedResultsController to respond to additions, removals and so on.
*/
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
if (!reordering) {
// The fetch controller is about to start sending change notifications, so prepare the table view for updates.
NSLog(@"controllerWillChangeContent:");
[self.tableView beginUpdates];
}
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
if (!reordering) {
NSLog(@"didChangeObject:");
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
NSLog(@"ResultsChangeInsert:");
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
/*case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;*/
}
}
}
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
if (!reordering) {
NSLog(@"didChangeSelection:");
switch(type) {
case NSFetchedResultsChangeInsert:
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
if (!reordering) {
NSLog(@"didChangeContent:");
// The fetch controller has sent all current change notifications, so tell the table view to process all updates.
[self.tableView endUpdates];
}else {
reordering = NO;
}
}
关于iphone - UITableView 中的 moveRowAtIndexPath 导致动画不正确,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4230353/