NSTreeController：“canInsert”的自定义行为绑定

发布于 2024-12-21 16:54:33 字数 768 浏览 3 评论 0原文

我有一个 Cocoa 应用程序，其中有一个由 NSTreeController 管理的 NSOutlineView。

此外，还有一个用于向大纲视图添加新元素的按钮。我将按钮的 enabled 标志绑定到树控制器的 canInsert 属性。

我只想允许向大纲视图添加最多 5 个元素。之后，canInsert 应返回 NO。

我创建了自己的NSTreeController子类并覆盖了canInsert，但是按钮的启用状态没有改变，因为它没有意识到树控制器已经改变添加元素时。

我还实现了：keyPathsForValuesAffectingCanInsert并尝试返回各种属性，例如content、arrangedObjects，但这里没有运气。

@implementation ILCustomTreeController

- (BOOL)canInsert
{
    return [[self arrangedObjects] count] < 5;
}

+ (NSSet *)keyPathsForValuesAffectingCanInsert
{
    return [NSSet setWithObject:@"content"]; // I also tried 'arrangedObjects'
}

@end

原文

I have a Cocoa app with an NSOutlineView managed by an NSTreeController.

In addition there's a button for adding new elements to the outline view. I bound the button's enabled flag to the tree controller's canInsert property.

I only want to allow adding up to 5 elements to the outline view. After that, canInsert should return NO.

I created my own sub-class of NSTreeController and overwrote canInsert, but the enabled status of the button does not change, because it doesn't realize that the tree controller has changed when adding elements.

I also implemented: keyPathsForValuesAffectingCanInsert and tried returning various properties such as content, arrangedObjects, but no luck here.

@implementation ILCustomTreeController

- (BOOL)canInsert
{
    return [[self arrangedObjects] count] < 5;
}

+ (NSSet *)keyPathsForValuesAffectingCanInsert
{
    return [NSSet setWithObject:@"content"]; // I also tried 'arrangedObjects'
}

@end

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暗喜 2024-12-28 16:54:34

这是一个可行的解决方法（尽管我仍然认为这应该通过使用 keyPathForValuesAffectingCanInsert 来解决）。欢迎提出建议。

@implementation ILCustomTreeController

- (BOOL)canInsert
{    
    return [[self arrangedObjects] count] <= 4;
}

- (void)addObject:(id)object
{
    [self willChangeValueForKey:@"canInsert"];
    [super addObject:object];
    [self didChangeValueForKey:@"canInsert"];
}

- (void)insertObject:(id)object atArrangedObjectIndexPath:(NSIndexPath *)indexPath
{
    [self willChangeValueForKey:@"canInsert"];
    [super insertObject:object atArrangedObjectIndexPath:indexPath];
    [self didChangeValueForKey:@"canInsert"];
}

- (void)remove:(id)sender
{
    [self willChangeValueForKey:@"canInsert"];
    [super remove:sender];
    [self didChangeValueForKey:@"canInsert"];    
}

@end

Here's a workaround that does work (although I still think this should be solved by using keyPathForValuesAffectingCanInsert). Suggestions are welcome.

@implementation ILCustomTreeController

- (BOOL)canInsert
{    
    return [[self arrangedObjects] count] <= 4;
}

- (void)addObject:(id)object
{
    [self willChangeValueForKey:@"canInsert"];
    [super addObject:object];
    [self didChangeValueForKey:@"canInsert"];
}

- (void)insertObject:(id)object atArrangedObjectIndexPath:(NSIndexPath *)indexPath
{
    [self willChangeValueForKey:@"canInsert"];
    [super insertObject:object atArrangedObjectIndexPath:indexPath];
    [self didChangeValueForKey:@"canInsert"];
}

- (void)remove:(id)sender
{
    [self willChangeValueForKey:@"canInsert"];
    [super remove:sender];
    [self didChangeValueForKey:@"canInsert"];    
}

@end

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