我遇到的问题是我有一个带有拖放功能的 NSOutlineView（请参阅帖子底部的代码以使拖放工作），它可以工作，但是当我将一行拖到另一行时，拖动的行变成了一个孩子，但它也停留在它作为父级的位置，当我删除任一行时，它们都会被删除。为了向您展示我的意思，我已经记录了问题，这是链接 - http://dvlp.me/6kya9
这是使拖放工作在大纲视图中的代码。
头文件。
@interface _NSControllerTreeProxy : NSObject
{
// opaque
}
//
// Number of objects at the root level.
//
- (unsigned int)count;
- (id)nodeAtIndexPath:(id)fp8;
- (id)objectAtIndexPath:(id)fp8;
@end
@interface _NSArrayControllerTreeNode : NSObject
{
// opaque
}
- (unsigned int)count;
- (id)observedObject;
- (id)parentNode;
- (id)nodeAtIndexPath:(id)fp8;
- (id)subnodeAtIndex:(unsigned int)fp8;
- (BOOL)isLeaf;
- (id)indexPath;
- (id)objectAtIndexPath:(id)fp8;
@end
// some more detailed reverse engineering is available here
// http://www.blueboxmoon.com/wiki/?page=Binding%20Tree
@interface DragController : NSObject
{
IBOutlet NSTreeController *groupTreeControl;
IBOutlet NSOutlineView *treeTable;
NSArray* dragType;
_NSArrayControllerTreeNode* draggedNode;
}
- (void) resortGroups:(NSManagedObjectContext*)objectContext forParent:(NSManagedObject*)parent;
- (NSArray* ) getSubGroups:(NSManagedObjectContext*)objectContext forParent:(NSManagedObject*)parent;
- (BOOL) category:(NSManagedObject* )cat isSubCategoryOf:(NSManagedObject* ) possibleSub;
@end
#define INTERVAL 10
实施文件。
@implementation DragController
- (void)awakeFromNib {
dragType = [NSArray arrayWithObjects: @"factorialDragType", nil];
[ dragType retain ];
[ treeTable registerForDraggedTypes:dragType ];
NSSortDescriptor* sortDesc = [[NSSortDescriptor alloc] initWithKey:@"position" ascending:YES];
[groupTreeControl setSortDescriptors:[NSArray arrayWithObject: sortDesc]];
[ sortDesc release ];
}
//------------------------------------
#pragma mark NSOutlineView datasource methods -- see NSOutlineViewDataSource
//---------------------------------------------------------------------------
- (BOOL) outlineView : (NSOutlineView *) outlineView
writeItems : (NSArray*) items
toPasteboard : (NSPasteboard*) pboard {
[ pboard declareTypes:dragType owner:self ];
// items is an array of _NSArrayControllerTreeNode see http://theocacao.com/document.page/130 for more info
draggedNode = [ items objectAtIndex:0 ];
return YES;
}
- (BOOL)outlineView:(NSOutlineView *)outlineView acceptDrop:(id <NSDraggingInfo>)info item:(id)item childIndex:(int)index {
_NSArrayControllerTreeNode* parentNode = item;
_NSArrayControllerTreeNode* siblingNode;
_NSControllerTreeProxy* proxy = [ groupTreeControl arrangedObjects ];
NSManagedObject* draggedGroup = [ draggedNode observedObject ];
BOOL draggingDown = NO;
BOOL isRootLevelDrag = NO;
// ----------------------
// Setup comparison paths
// -------------------------
NSIndexPath* draggedPath = [ draggedNode indexPath ];
NSIndexPath* siblingPath = [ NSIndexPath indexPathWithIndex: index ];
if ( parentNode == NULL ) {
isRootLevelDrag = YES;
} else {
// A non-root drag - the index value is relative to this parent's children
siblingPath = [ [ parentNode indexPath ] indexPathByAddingIndex: index ];
}
// ----------------------
// Compare paths - modify sibling path for down drags, exit for redundant drags
// -----------------------------------------------------------------------------
switch ( [ draggedPath compare:siblingPath] ) {
case NSOrderedAscending: // reset path for down dragging
if ( isRootLevelDrag ) {
siblingPath = [ NSIndexPath indexPathWithIndex: index - 1];
} else {
siblingPath = [ [ parentNode indexPath ] indexPathByAddingIndex: index - 1 ];
}
draggingDown = YES;
break;
case NSOrderedSame:
return NO;
break;
}
siblingNode = [ proxy nodeAtIndexPath:siblingPath ];
// NSLog(@"returning early");
// return NO; // TODO robustify
// ------------------------------------------------------------
// SPECIAL CASE: Dragging to the bottom
// ------------------------------------------------------------
// - K - K - C - C
// - - U - - C OR - U - F
// - - C ====> - - F - F - K
// - - F - U - K - U
// ------------------------------------------------------------
if ( isRootLevelDrag && siblingNode == NULL ) {
draggingDown = YES;
siblingPath = [ NSIndexPath indexPathWithIndex: [ proxy count ] - 1 ];
siblingNode = [ proxy nodeAtIndexPath:siblingPath ] ;
}
// ------------------------------------------------------------
// Give the dragged item a position relative to it's new sibling
// ------------------------------------------------------------
NSManagedObject* sibling = [ siblingNode observedObject ];
NSNumber* bystanderPosition = [ sibling valueForKey:@"position"];
int newPos = ( draggingDown ? [ bystanderPosition intValue ] + 1 : [ bystanderPosition intValue ] - 1 );
[draggedGroup setValue:[ NSNumber numberWithInt:newPos ] forKey:@"position"];
// ----------------------------------------------------------------------------------------------
// Set the new parent for the dragged item, resort the position attributes and refresh the tree
// ----------------------------------------------------------------------------------------------
[ draggedGroup setValue:[ parentNode observedObject ] forKey:@"parent" ];
[ self resortGroups:[draggedGroup managedObjectContext] forParent:[ parentNode observedObject ] ];
[ groupTreeControl rearrangeObjects ];
return YES;
}
- (NSArray* ) getSubGroups:(NSManagedObjectContext*)objectContext forParent:(NSManagedObject*)parent {
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"projects" inManagedObjectContext:objectContext];
[request setEntity:entity];
NSSortDescriptor* aSortDesc = [[NSSortDescriptor alloc] initWithKey:@"position" ascending:YES];
[request setSortDescriptors:[NSArray arrayWithObject: aSortDesc] ];
[aSortDesc release];
NSPredicate* validationPredicate = [NSPredicate predicateWithFormat:@"parent == %@", parent ];
[ request setPredicate:validationPredicate ];
NSError *error = nil; // TODO - check the error bozo
return [objectContext executeFetchRequest:request error:&error];
}
- (void) resortGroups:(NSManagedObjectContext*)objectContext forParent:(NSManagedObject*)parent {
NSArray *array = [ self getSubGroups:objectContext forParent:parent ];
// Reset the indexes...
NSEnumerator *enumerator = [array objectEnumerator];
NSManagedObject* anObject;
int index = 0;
while (anObject = [enumerator nextObject]) {
// Multiply index by 10 to make dragging code easier to implement ;) ....
[anObject setValue:[ NSNumber numberWithInt:(index * INTERVAL ) ] forKey:@"position"];
index++;
}
}
- (NSDragOperation)outlineView:(NSOutlineView *)outlineView validateDrop:(id <NSDraggingInfo>)info proposedItem:(id)item proposedChildIndex:(int)index {
_NSArrayControllerTreeNode* newParent = item;
// drags to the root are always acceptable
if ( newParent == NULL ) {
return NSDragOperationGeneric;
}
// Verify that we are not dragging a parent to one of it's ancestors
// causes a parent loop where a group of nodes point to each other and disappear
// from the control
NSManagedObject* dragged = [ draggedNode observedObject ];
NSManagedObject* newP = [ newParent observedObject ];
if ( [ self category:dragged isSubCategoryOf:newP ] ) {
return NO;
}
return NSDragOperationGeneric;
}
- (BOOL) category:(NSManagedObject* )cat isSubCategoryOf:(NSManagedObject* ) possibleSub {
// Depends on your interpretation of subCategory ....
if ( cat == possibleSub ) { return YES; }
NSManagedObject* possSubParent = [possibleSub valueForKey:@"parent"];
if ( possSubParent == NULL ) { return NO; }
while ( possSubParent != NULL ) {
if ( possSubParent == cat ) { return YES; }
// move up the tree
possSubParent = [possSubParent valueForKey:@"parent"];
}
return NO;
}
// This method gets called by the framework but the values from bindings are used instead
- (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)item {
return NULL;
}
/*
The following are implemented as stubs because they are required when
implementing an NSOutlineViewDataSource. Because we use bindings on the
table column these methods are never called. The NSLog statements have been
included to prove that these methods are not called.
*/
- (int)outlineView:(NSOutlineView *)outlineView numberOfChildrenOfItem:(id)item {
NSLog(@"numberOfChildrenOfItem");
return 1;
}
- (BOOL)outlineView:(NSOutlineView *)outlineView isItemExpandable:(id)item {
NSLog(@"isItemExpandable");
return NO;
}
- (id)outlineView:(NSOutlineView *)outlineView child:(int)index ofItem:(id)item {
NSLog(@"child of Item");
return NULL;
}
@end