我有一个数组,其中包含几个带有键的NSDictionaries:
> NSString *名称
> NSString * ID
> NSDictionary * phoneNumbersDict
现在我想过滤这个数组,找到一个具有phoneNumbersDict键@“keyIAmLookingFor”和值@“valueIAmLookingFor”的数组.
- NSMutableArray *addressBookPhoneIndividuals = [NSMutableArray array];
- for (int i = 0; i < x; i++) {
- [addressBookPhoneIndividuals addObject:@{
- @"name" : @"...",@"ID" : @"...",@"phoneNumbers" : @{...}
- }];
- }
解决方法
- 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“Eric Johnson”字典的数组.
我喜欢在进行任何类型的复杂匹配时推荐NSComparisonPredicate.查看修改器,类型和选项的选项.那里有一些很好的内置匹配引擎 – 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,所以你可以替换以下内容:
- NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K = %@",keyPath,valueIAmLookingFor];
如果您只关心第一个结果,则可以完全跳过keyPath /谓词业务:
- for (NSDictionary *individualDict in addressBookPhoneIndividuals) {
- NSDictionary *phoneNumbers = [individualDict objectForKey:@"phoneNumbers"];
- NSString *possibleMatch = [phoneNumbers objectForKey:keyIAmLookingFor];
- if ([possibleMatch isEqualToString:valueIAmLookingFor]) {
- return individualDict;
- }
- }
- return nil;