多个NSPredicate [英] Multiple NSPredicate

问题描述

我正在尝试在我的CoreData实体食谱中准备多个搜索.有一些我要准备获取的参数.

I'm trying to prepare multiple search in my CoreData entity Recipes. There are parameters by which I would like to prepare fetch.

食谱属性:

@property (nonatomic, retain) NSNumber * difficulty;
@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSNumber * code; //like identifier
@property (nonatomic, retain) NSNumber * prepTime;

成分是带有成分列表的单独实体.

Ingredients is a separate entity with the list of ingredients.

加入实体包含成分代码，密码，计数.

getArrayOfJoinDataWithIngredients 获取 join 实体，并返回包含某些输入成分的配方的代码的NSArray.

getArrayOfJoinDataWithIngredients fetches join entity and returns NSArray of codes of recipes which contains some of input ingredient.

这是我的代码:

- (IBAction)callRecipeFetch:(id)sender
{
    NSString *predicateString = @"";

    NSArray *codes = [[NSArray alloc] init]; codes = nil;
    if ([paramController.ingredientsForSearchArray count] > 0) {
        NSMutableArray *ingredientsArray = [[NSMutableArray alloc] init];
        for (Ingredients *ingredient in paramController.ingredientsForSearchArray) {
            [ingredientsArray addObject:ingredient.code];
        }
        MainTabController *mainTabController = [[MainTabController alloc] init];
        codes = [mainTabController getArrayOfJoinDataWithIngredients:ingredientsArray];

        NSString *ingrSet = [NSString stringWithFormat:@"(code IN %@)", codes];
        predicateString = [predicateString stringByAppendingString:ingrSet];
    }

    NSString *diff;
    if ([predicateString isEqualToString:@""]) {
        diff = [NSString stringWithFormat:@"(difficulty <= %d)", paramController.diff.selectedSegmentIndex + 1];
    }
    else diff = [NSString stringWithFormat:@" AND (difficulty <= %d)", paramController.diff.selectedSegmentIndex + 1];
    predicateString = [predicateString stringByAppendingString:diff];

    NSString *timeString = [NSString stringWithFormat:@" AND (%d =< prepTime) AND (prepTime <= %d)", paramController.rangeSlider.leftValue, paramController.rangeSlider.rightValue];
    predicateString = [predicateString stringByAppendingString:timeString];

    if (paramController.categoryCode) {
        NSString *categoryString = [NSString stringWithFormat:@" AND (inCategory = %@)", paramController.categoryCode];
        predicateString = [predicateString stringByAppendingString:categoryString];
    }

    NSPredicate *predicate = [NSPredicate predicateWithFormat: predicateString];
    [resultController findRecipesWithPredicate:predicate];
}

完整的predicateString是@"(code IN (\n 1,\n 3\n)) AND (difficulty <= 5) AND (0 =< prepTime) AND (prepTime <= 28800) AND (inCategory = 12)"

The full predicateString is @"(code IN (\n 1,\n 3\n)) AND (difficulty <= 5) AND (0 =< prepTime) AND (prepTime <= 28800) AND (inCategory = 12)"

现在，当我使用代码准备NSPredicate时，谓词部分(代码输入％@)中出现错误:

Now I have an error in predicate part (code IN %@) when I prepare NSPredicate with code:

NSPredicate *predicate = [NSPredicate predicateWithFormat: predicateString];

错误:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable     to parse the format string "(code IN (
1,
3
)) AND (difficulty <= 5) AND (0 =< prepTime) AND (prepTime <= 28800) AND (inCategory =  12)"'

如何正确地使用 IN 谓词.感谢您的所有建议.

How to correctly make predicate with IN operator. Thanks for all advices.

推荐答案

对多个谓词使用NSCompoundPredicate，您可以引用NSCompoundPredicate类参考

use NSCompoundPredicate for your multiple predicates, you can refer NSCompoundPredicate Class Reference

类似这样的东西:

NSPredicate * andPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:predicate1,predicate2,predicate3,nil]];

这篇关于多个NSPredicate的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！