用数组的顺序在子句中对NSPredicate进行排序 [英] Sort NSPredicate with in clausule with array's order

问题描述

我有一个 NSPredicate ，它在 NSArray 的ids，
某物内搜索id像

I have a NSPredicatethat does a search of id within an NSArrayof ids, something like

（'id in％@'，array）

有没有办法以相同的数组顺序对获取的结果集进行排序？

Is there a way to get the resultset of that fetch sorted with the same array's order?

我现在拥有的代码是

+(NSArray*)     findIn:(NSArray*)identifiers{

    if(identifiers == nil) return nil;

    NSPredicate *searchFilter   = [NSPredicate predicateWithFormat:@"id IN %@", identifiers];
    NSArray     *fetchedObjects =  [GSBaseModel setupFetch:[[self class] managedObjectEntityName] andFilter:searchFilter andSortKey:nil];

    if([fetchedObjects count] == 0){
        return nil;
    }
    return fetchedObjects;
}

setupfecth会执行以下操作：

The setupfecth just does the following:

NSFetchRequest      *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity   = [NSEntityDescription entityForName:entityName inManagedObjectContext:[NSManagedObjectContext MR_defaultContext]];
[fetchRequest setEntity:entity];
return  = [[NSManagedObjectContext MR_defaultContext] executeFetchRequest:fetchRequest error:&error];

推荐答案

我终于这样解决了

感谢根据另一个NSArray字符串的排序对自定义对象的NSArray进行排序

+(NSArray*)sortWithArray:(NSArray*)toSort sorted:(NSArray*)sortedIdentifiers{
    NSMutableArray *sorted = [NSMutableArray array];

    // pre-populate with objects
    for (int i = 0; i < sortedIdentifiers.count; i++)
    {
        [sorted addObject:[NSNull null]];
    }
    // place the items at the correct position
    for (NSManagedObject *a in toSort)
    {
        NSNumber* identifier = [a valueForKey:@"id"];
        NSUInteger idx = [sortedIdentifiers indexOfObject:[identifier stringValue]];
        if (idx != NSNotFound)
        {
            [sorted setObject:a atIndexedSubscript:idx];
        }
    }
    // finally remove all the unecesarry placeholders if one array was smaller
    [sorted removeObject:[NSNull null]];
    return sorted;
}

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