如何过滤NSDictionary和NSDictionary的数组？ [英] How can I filter an array of NSDictionarys and NSDictionarys?

问题描述

我有一个数组，其中包含几个 NSDictionaries ，它们的键为：

I have an array which consists of several NSDictionaries with the keys:

• NSString *名称


• NSString * ID


• NSDictionary * phoneNumbersDict

• NSString *name
• NSString *ID
• NSDictionary *phoneNumbersDict

现在我要过滤此数组以找到一个具有 phoneNumbersDict 键 @ keyIAmLookingFor 和值 @ valueIAmLookingFor 。

Now I want to filter this array to find the one which has the phoneNumbersDict key @"keyIAmLookingFor" and the value @"valueIAmLookingFor".

NSMutableArray *addressBookPhoneIndividuals = [NSMutableArray array];
for (int i = 0; i < x; i++) {
    [addressBookPhoneIndividuals addObject:@{
        @"name" : @"...",
        @"ID" : @"...",
        @"phoneNumbers" : @{...}
    }];
}

推荐答案

NSString *keyIAmLookingFor = @"work";
NSString *valueIAmLookingFor = @"444-567-9019";

NSArray *addressBookPhoneIndividuals = @[
    @{
        @"name" : @"Mike Rowe",
        @"ID" : @"134",
        @"phoneNumbers" : @{
            @"work" : @"123-456-8000",
            @"school" : @"647-5543",
            @"home" : @"123-544-3321",
        }
    },
    @{
        @"name" : @"Eric Johnson",
        @"ID" : @"1867",
        @"phoneNumbers" : @{
            @"work" : @"444-567-9019",
            @"other" : @"143-555-6655",
        }
    },
    @{
        @"name" : @"Robot Nixon",
        @"ID" : @"-12",
        @"phoneNumbers" : @{
            @"work" : @"123-544-3321",
            @"school" : @"123-456-8000",
            @"home" : @"444-567-9019",
        }
    },
];

NSString *keyPath = [@"phoneNumbers." stringByAppendingString:keyIAmLookingFor];

NSPredicate *predicate =
[NSComparisonPredicate predicateWithLeftExpression:[NSExpression expressionForKeyPath:keyPath]
                                   rightExpression:[NSExpression expressionForConstantValue:valueIAmLookingFor]
                                          modifier:NSDirectPredicateModifier
                                              type:NSEqualToPredicateOperatorType
                                           options:0];

NSArray *result = [addressBookPhoneIndividuals filteredArrayUsingPredicate:predicate];

这将返回包含埃里克·约翰逊字典的数组。

This will return an array containing the "Eric Johnson" dictionary.

在进行任何类型的复杂匹配时，我建议使用 NSComparisonPredicate 。查看修饰符，类型和选项的选项。那里有一些内置的匹配引擎，包括正则表达式和不区分大小写。无论如何，这里可能没有必要，所以您可以替换以下内容：

I like to recommend NSComparisonPredicate when doing any kind of complex matching. Look at the options for modifier, type and options. There are some good built in matching engines in there - including regular expressions and case insensitivity. Anyway, it probably isn't necessary here, so you could substitute the following:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K = %@", keyPath, valueIAmLookingFor];

如果只关心第一个结果，则可以完全跳过keyPath /谓词业务：

If you only care about the first result, you can skip the keyPath/predicate business altogether:

for (NSDictionary *individualDict in addressBookPhoneIndividuals) {
    NSDictionary *phoneNumbers = [individualDict objectForKey:@"phoneNumbers"];
    NSString *possibleMatch = [phoneNumbers objectForKey:keyIAmLookingFor];
    if ([possibleMatch isEqualToString:valueIAmLookingFor]) {
        return individualDict;
    }
}

return nil;

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