多个NSPredicate

Question

我正在尝试为我的CoreData实体Recipes准备多个搜索。 我希望通过某些参数来准备获取。

Recipes属性：

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

Ingredients是一个包含食材清单的单独实体。

Join实体包括ingredientCode、recipeCode和count。

getArrayOfJoinDataWithIngredients获取join实体，并返回包含一些输入食材的配方codes数组NSArray。

以下是我的代码:

- (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)"

现在，在准备使用代码创建NSPredicate时，predicate部分(code IN %@)出现错误:

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)"'

如何使用IN运算符正确制作谓词。感谢所有建议。

- Romowski

Answer 1

使用NSCompoundPredicate来处理多个谓词，你可以参考NSCompoundPredicate Class Reference

例如：

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

- Joshua

Answer 2

除了@Joshua的答案外，您还可以使用NSCompoundPredicate进行OR操作，方法如下：

Obj-C - OR

// OR Condition //

NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"X == 1"];
NSPredicate *predicate2 = [NSPredicate predicateWithFormat:@"X == 2"];
NSPredicate *predicate = [NSCompoundPredicate orPredicateWithSubpredicates:@[predicate1, predicate2]];

Swift - OR

在Swift编程语言中，“OR”是一个逻辑运算符，用于比较两个布尔值。当任意一个布尔值为真时，表达式的结果为真。

let predicate1:NSPredicate = NSPredicate(format: "X == 1")
let predicate2:NSPredicate = NSPredicate(format: "Y == 2")
let predicate:NSPredicate  = NSCompoundPredicate(orPredicateWithSubpredicates: [predicate1,predicate2] )

Swift 3 - OR

    let predicate1 = NSPredicate(format: "X == 1")
    let predicate2 = NSPredicate(format: "Y == 2")
    let predicateCompound = NSCompoundPredicate.init(type: .or, subpredicates: [predicate1,predicate2])

- Onur Var

Answer 3

这对你来说是可行的。

    NSPredicate *bPredicate;
    bPredicate = [NSPredicate predicateWithFormat:@"name contains[c] %@ OR product_price contains[c] %@ OR foodescription contains[c] %@",searchText,searchText,searchText];

NSArray *filteredArray = [getObjectsFromServiceArray filteredArrayUsingPredicate:bPredicate];

- Noman Yousuf