Re: reloading an NSTreeController

[Jonathan Dann]

On 1 Aug 2008, at 14:04, Gerriet M. Denkmann wrote:

But all disclosure triangels are now closed. Is there some way to reopen them to the previous state? I have the strong feeling that I will have to handle this myself. Ok. So be it.

It's a common problem.  Can I point you here:

http://www.cocoabuilder.com/archive/message/cocoa/2008/2/23/199705

        int numberOfRows = [ outlineView numberOfRows ];
        for( int row = 0; row < numberOfRows; row++ )
        {

                BOOL isExpanded = [ outlineView isItemExpanded: item ];
                if (isExpanded)
                {
                        NSString *key = [ item valueForKey: @"Key" ]; <--- does 
not work.
                };
        };

id item = [ outlineView itemAtRow: row ]; // _NSArrayControllerTreeNode The objects in myContentArray are key value coding-compliant for the key Key. But I get the error message: [<_NSArrayControllerTreeNode 0x3f1fd0> valueForUndefinedKey:]: this class is not key value coding-compliant for the key Key.

This will not work as in the line:

NSString *key = [ item valueForKey: @"Key" ];

you're effectively doing this:

NSString *key = [item Key];



http://developer.apple.com/documentation/Cocoa/Conceptual/KeyValueCoding/KeyValueCoding.html

If, for example I were to have the class:

@interface MyClass : NSObject {
NSArray *myArray;
}
- (void)setMyArray:(NSArray *)newValue;
- (NSArray *)myArray;
@end

Then I could safely do this:

MyClass *item = [[[MyClass alloc] init] autorelease];
NSArray *anArray = [item valueForKey:@"myArray"];

or
NSString *key = @"myArray";
MyClass *item = [[[MyClass alloc] init] autorelease];
NSArray *anArray = [item valueForKey:key];




Hope this helps,

Jonathan

http://espresso-served-here.com

which clearly won't work as whatever class your 'item' is doesn't have a method with the signature: Key. For this to work you'd need -Key (and then likely -setKey:) in your class. I'd have another look at the documentation on KVC. Having said all this, isn't _NSArrayControllerTreeNode private, with all the caveats that apply to using private classes. You're not guaranteed that instances of this class with respond to *anything*.

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