NSSortDescriptor - 将＃和数字推到列表的末尾 - iphone xcode [英] NSSortDescriptor - push # and numbers to the end of the list - iphone xcode

问题描述

我有一个表格视图，显示按字母顺序排序的联系人，并将其划分为部分。

I have a table view that shows contacts sorted by alphabetic ordering and divide it to sections.

我正在使用 -

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:[dataSource keyName] ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];

然后对于没有姓名的联系人我使用＃符号作为他们的第一个字母，所以所有这些都将被分组在一个小组中。

then for contacts without name i am using # sign as their first letter so all of them will be grouped in one group.

一切都很棒。我唯一想要的就是将＃部分推到表的末尾，就像现在它显示在它的开头一样。

everything is great. the only thing i want is to push the # section to the end of the table, as for now it shows in the beginning of it.

任何想法？

提前感谢

shani

推荐答案

执行此操作的最佳方法是使用sortDescriptorWithKey：ascending：comparator：方法创建自己的自定义排序描述符。这使您可以创建自己的比较函数，使用块指定。

The best way to do this is to create your own custom sort descriptor using the sortDescriptorWithKey:ascending:comparator: method. This lets you create your own comparison function, which you specify using a block.

首先，创建一个比较函数。如果您之前从未使用块编程是时候学习了！

First, create a comparison function. If you've never programmed with blocks before, now is the time to learn!

NSComparisonResult (^myStringComparison)(id obj1, id obj2) = ^NSComparisonResult(id obj1, id obj2) {

    // Get the first character of the strings you're comparing
    char obj1FirstChar = [obj1 characterAtIndex:0];
    char obj2FirstChar = [obj2 characterAtIndex:0];

    // Check if one (but not both) strings starts with a '#', and if so, make sure that one is sorted below the other
    if (obj1FirstChar  == '#' && obj2FirstChar != '#') {
        return NSOrderedDescending;
    } else if (obj2FirstChar == '#' && obj1FirstChar != '#') {
        return NSOrderedAscending;
    } 
    // Otherwise return the default sorting order
    else {
        return [obj1 compare:obj2 options:0];
    }
};

现在您已经拥有了比较功能，您可以使用它来创建排序描述符：

Now that you have your comparison function, you can use it to create a sort descriptor:

NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:[dataSource keyName] ascending:YES comparator:myStringComparison];

您现在可以像使用其他任何一样使用该排序描述符，并且您的列表将具有＃物品排序到最后！

You can now use that sort descriptor just like you would any other, and your list will have the # items sorted to the end!

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