Filtering A Tree Controller - objective-c

Question

I have now nearly figured out how to Filter a NSTreeController, to do this I have sub-classed NSManagedObject and added some code to my App Delegate, I have also bound my NSSearchField to the filterPredicate of my App Delegate but I think I need to connect my NSTreeController and NSSearchField in some way to make it work.
Below I have posted all the code I have used so far to try and make it work.
NSManagedObject Sub-Class Header File.
#interface Managed_Object_Sub_Class : NSManagedObject {
NSArray *filteredChildren; // this should fix the compiler error
}
- (NSArray *)filteredChildren;
#end
NSManagedObject Sub-Class Implementation File.
#implementation Managed_Object_Sub_Class
static char *FilteredChildrenObservationContext;
- (id)initWithEntity:(NSEntityDescription *)entity insertIntoManagedObjectContext:(NSManagedObjectContext *)context {
if (self = [super initWithEntity:entity insertIntoManagedObjectContext:context]) {
[[NSApp delegate] addObserver:self forKeyPath:#"filterPredicate" options:0 context:&FilteredChildrenObservationContext];
[self addObserver:self forKeyPath:#"subGroup" options:0 context:&FilteredChildrenObservationContext];
}
return self;
}
// use finalize with GC
- (void)dealloc {
[[NSApp delegate] removeObserver:self forKeyPath:#"filterPredicate"];
[self removeObserver:self forKeyPath:#"subGroup"];
[super dealloc];
}
- (NSArray *)filteredChildren {
if (filteredChildren == nil) {
NSPredicate *predicate = [[NSApp delegate] filterPredicate];
if (predicate)
filteredChildren = [[[self valueForKey:#"subGroup"] filteredArrayUsingPredicate:predicate] copy];
else
filteredChildren = [[self valueForKey:#"subGroup"] copy];
}
return filteredChildren;
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if (context == &FilteredChildrenObservationContext) {
[self willChangeValueForKey:#"filteredChildren"];
[filteredChildren release];
filteredChildren = nil;
[self didChangeValueForKey:#"filteredChildren"];
} else {
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}
#end
Code Added To App Delegate Header File
NSPredicate *filterPredicate;
Code Added To App Delegate Implementation File
- (NSPredicate *)filterPredicate {
return filterPredicate;
}
- (void)setFilterPredicate:(NSPredicate *)newFilterPredicate {
if (filterPredicate != newFilterPredicate) {
[filterPredicate release];
filterPredicate = [newFilterPredicate retain];
}
}
Search Field Binding
alt text http://snapplr.com/snap/vs9q
This doesn't work yet, and so that is why I am asking what I need to do from here to make it work, like I said I think I need to connect the NSSearchField and NSTreeController Together in some way.

Answer 1

Again I hav answered my own question, I also hope that this will help other people so they know how to Filter a NSTreeController.
To make it work from my post above do the following.
1.For your entity set the Class as your NSManagedObject Sub-Class in my Case JGManagedObject.
alt text http://dvlp.me/c3k
2.For your search field in IB set the predicate format to what you want to Filter ( The Property in your entity, for me it is name).
alt text http://dvlp.me/9k9rw