如何在 iPhone 中按降序对数组进行排序 [英] How to sort an array in descending order in iPhone

问题描述

我正在尝试按降序对数组进行排序，我可以按升序对数组进行排序，这是我按升序排序的代码，

I am trying to sort an array in descending order,I can sort array in ascending order,Here is my code to sort in ascending order,

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"year" ascending:NO];
NSArray * descriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
sortedArray = [array sortedArrayUsingDescriptors:descriptors];

dictionaryWithSortedYears = [[NSMutableDictionary alloc] init];
NSString *tempDateKey = nil;

for (TreeXmlDetails *list in sortedArray)
{
    id obj = [dictionaryWithSortedYears objectForKey:list.year];

    if(!obj)
    {
        if(tempDateKey == nil)
        {
            arrayFromList = [[NSMutableArray alloc] init];
            tempDateKey = list.year;
        }
    }

    if([list.year isEqualToString:tempDateKey])
        [arrayFromList addObject:list];
    else
    {
        [dictionaryWithSortedYears setObject:arrayFromList forKey:tempDateKey];
        tempDateKey = nil;
        arrayFromList = nil;
        arrayFromList = [[NSMutableArray alloc] init];
        tempDateKey = list.year;
        [arrayFromList addObject:list];
    }
}

[dictionaryWithSortedYears setObject:arrayFromList forKey:tempDateKey];

NSArray *arr = [dictionaryWithSortedYears allKeys];

sortedKeys = [[NSArray alloc] initWithArray:[arr sortedArrayUsingSelector:@selector(compare:)]];

但是，我想按降序对数组进行排序，请帮帮我.提前致谢.

But, I want to sort an array in descending array,Please help me. Thanks in advnace.

推荐答案

使用以下内容:

[yourArrayToBeSorted sortUsingComparator:^NSComparisonResult(id obj1, id obj2){
    return [(NSDate *)obj2 compare:(NSDate *)obj1];} ];

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