在NSOutlineView拖放的問題

Question

我遇到的問題是我有一個NSOutlineView與拖放（見底部的代碼拖放工作），它的工作原理，但當我拖動一行拖到另一行拖動的行成爲一個孩子，但它也停留在它作爲父母的地方，當我刪除任何一行時，他們都被刪除。 要告訴你我的意思是，我記錄了這個問題，這裏是鏈接 - http://dvlp.me/6kya9

這裏是使阻力和在大綱視圖降工作的代碼。

頭文件。

@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 

Implemetation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 

Answer 1

剛做了一點四處搜尋，並找到了解決方法。 在NSTreeController的屬性中，將獲取謂詞設置爲parent == nil。