在nstableview列中将nil值行总是排在底部 [英] Sorting nil-valued rows always to bottom in nstableview column

问题描述

我在我的应用程序中有一个 NSTableview 包含几列。当我点击一个列标题以便按升序排序时，在该列中具有nil值的行将按顶部排序，然后按升序排列非零值行。如果我在同一列上重新点击，首先按降序显示非nil值的行，然后是nil值行。

I have an NSTableview in my application containing several columns. When I click on one column header in order to have it sorted ascending, rows with a nil-value in that column are being sorted on top followed by non-nil-valued rows in ascending order. If I reclick on the same column, first the non-nil-valued rows are being shown in descending order followed by nil-valued rows.

我想要做的是具有零值行总是粘在底部。因此，首先应该呈现以升序或降序排序的非零值行，并且应该将nil值行保持在底部。

What I want to do is having nil-valued rows always sticked to the bottom. So at first non-nil-valued rows being sorted in either ascending or descending way should be presented and nil-valued rows should be kept at the bottom. How can this be done the best way?

在这个上下文中排序 - 是我的理解 - 是由 NSArrayController arrangedObject：。因此，我应该将 NSArrayController 子类化，并在 arrangeObjects：方法中使用自定义排序算法，上述结果？

Sorting in this context - to my understand - is done by the NSArrayController's arrangedObject:. So should I subclass NSArrayController and use a custom sorting algorithm in arrangedObjects: method, or is there a better way to get the result described above?

推荐答案

非常感谢。正如我上面提到的，我总是希望nil值排序到底部我用compareObject：以下面的方式使用你的代码。

Thanks a lot. As I mentioned above I always want nil-values sorted to the bottom I used your code with compareObject: in the following way.

- (NSComparisonResult)compareObject:(id)object1 toObject:(id)object2 {
    if (NULL_OBJECT([object1 valueForKeyPath:[self key]]) && NULL_OBJECT([object2 valueForKeyPath:[self key]]))
        return NSOrderedSame;
    if (NULL_OBJECT([object1 valueForKeyPath:[self key]]))
        return NSOrderedDescending;
    if (NULL_OBJECT([object2 valueForKeyPath:[self key]]))
        return NSOrderedAscending;
    return [super compareObject:object1 toObject:object2];
}

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