On Feb 22, 2008, at 6:51 AM, Julius Eckert wrote:
Hi,
i am implementing a datasource for an nsoutlineview to represent the
contents of a simple tree-structure defined by the following class
(simplified):
@interface TBCatalogNode : NSObject {
NSMutableArray* children;
}
@property (readonly, retain) NSMutableArray* children;
(the array children is created by the constructor is definately
never nil)
my data source looks like this:
-(CatalogRepresentation*) initWithNode:(TBCatalogNode*)rootNode {
if (self = [super init]) {
root = [rootNode retain];
}
return self;
}
- (id)outlineView:(NSOutlineView *)outlineView child:(NSInteger)index
ofItem:(id)item {
TBCatalogNode* objItem = (item == nil) ? root : item;
return [[[objItem children] objectAtIndex:index] retain];
}
You are responsible for maintaining the life of the objects, not the
outline view. it does not retain/release the objects. It is incorrect
to have the last retain in there.
- (NSInteger)outlineView:(NSOutlineView *)outlineView
numberOfChildrenOfItem:(id)item {
return (item == nil) ? [[root children] count] : [[item children]
count];
}
- (BOOL)outlineView:(NSOutlineView *)outlineView isItemExpandable:
(id)item {
return ([self outlineView:outlineView
numberOfChildrenOfItem:item] > 0);
}
- (id)outlineView:(NSOutlineView *)outlineView
objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:
(id)item {
TBCatalogNode* objItem = (item == nil) ? root : item;
return [[[objItem preset] info] objectForKey:@"ID"]; // this
line gets
a string from a nsdictionary
}
This code works perfect with the garbage collection activated. when i
disable the gc it is working just at the begining, it shows the
first level
under the root. when i click to expand an item it crashes ->
debugger is
telling me at numberOfChildrenOfItem: - function.
I dont know what in the background is going on as I am pretty new to
OSX. I
guess it is about some memory management, threading ?! I tried to
retain
nearly everything, and I am running out of ideas.
Your model, the TBCatalogNode, needs to retain all the children (which
it probably does). You are probably doing something wrong when
inserting children into your model.
corbin
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