我很难拼凑足够多的知识片段来实现一个 NSOutlineView,它具有在 NSArray 中定义的静态、永不改变的结构。这个链接很棒,但它并没有帮助我掌握子菜单。我认为它们只是嵌套的 NSArrays,但我不清楚。
假设我们在 NSArray 中有一个 NSArray,定义为
NSArray *subarray = [[NSArray alloc] initWithObjects:@"2.1", @"2.2", @"2.3", @"2.4", @"2.5", nil];
NSArray *ovStructure = [[NSArray alloc] initWithObjects:@"1", subarray, @"3", nil];
文本在 outlineView:objectValueForTableColumn:byItem: 中定义。
- (id)outlineView:(NSOutlineView *)ov objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)ovItem
{
if ([[[tableColumn headerCell] stringValue] compare:@"Key"] == NSOrderedSame)
{
// Return the key for this item. First, get the parent array or dictionary.
// If the parent is nil, then that must be root, so we'll get the root
// dictionary.
id parentObject = [ov parentForItem:ovItem] ? [ov parentForItem:ovItem] : ovStructure;
if ([parentObject isKindOfClass:[NSArray class]])
{
// Arrays don't have keys (usually), so we have to use a name
// based on the index of the object.
NSLog([NSString stringWithFormat:@"%@", ovItem]);
//return [NSString stringWithFormat:@"Item %d", [parentObject indexOfObject:ovItem]];
return (NSString *) [ovStructure objectAtIndex:[ovStructure indexOfObject:ovItem]];
}
}
else
{
// Return the value for the key. If this is a string, just return that.
if ([ovItem isKindOfClass:[NSString class]])
{
return ovItem;
}
else if ([ovItem isKindOfClass:[NSDictionary class]])
{
return [NSString stringWithFormat:@"%d items", [ovItem count]];
}
else if ([ovItem isKindOfClass:[NSArray class]])
{
return [NSString stringWithFormat:@"%d items", [ovItem count]];
}
}
return nil;
}
结果是“1”、“(”(可扩展)和“3”。NSLog 显示以“(”开头的数组,因此是第二项。扩展它会由于“超出界限”而导致崩溃。我尝试使用parentForItem:但无法弄清楚将结果与什么进行比较。
我错过了什么?