如何在 NSPredicate 中评估 NSDictionary

Question

我有一个字典有两个数组，字典是

NSDictionary * StudentDetails = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:StudentIDs,StudentNames, nil] forKeys:[NSArray arrayWithObjects:@"ID",@"NAME", nil]];

两个数组是

NSArray * StudentIDs = [NSArray arrayWithObjects:@"07bg1234",@"07ac1234", nil];
NSArray * StudentNames = [NSArray arrayWithObjects:@"aaaaaaa",@"bbbbb", nil];

我尝试使用谓词来检索数组值

NSString * searchStr = @"07bg1234";

    NSPredicate * fileExtPredicate01 = [NSPredicate predicateWithFormat:@"SELF IN %@", StudentIDs];

    if (([fileExtPredicate01 evaluateWithObject: searchStr]== YES)) {
        NSLog(@"Student ID: %@ Exists",searchStr);
    }
    else {
        NSLog(@"Student ID: %@ not Exists",searchStr);
    }

到目前为止，它工作正常....当我尝试将字典值获取为时

NSPredicate * fileExtPredicate02 = [NSPredicate predicateWithFormat:@"SELF IN %@", StudentDetails];

    if (([fileExtPredicate02 evaluateWithObject: searchStr]== YES)) {
        NSLog(@"Student Details: %@ Exists",searchStr);
    }
    else {
        NSLog(@"Student Details: %@ not Exists",searchStr);
    }

我总是得到 o/p 作为学生详细信息 **** 不存在...我如何使用谓词在字典中获取“searchStr”？？？？？提前谢谢你

Answer 1

使用@"SELF IN %@.ID"。

我构建了以下通过单元测试。

NSArray * StudentIDs = [NSArray arrayWithObjects:@"07bg1234",@"07ac1234", nil];
NSArray * StudentNames = [NSArray arrayWithObjects:@"aaaaaaa",@"bbbbb", nil];
NSDictionary * StudentDetails = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:StudentIDs,StudentNames, nil] forKeys:[NSArray arrayWithObjects:@"ID",@"NAME", nil]];
NSString *searchStr = @"07bg1234";

NSPredicate * fileExtPredicate02 = [NSPredicate predicateWithFormat:@"SELF IN %@.ID", StudentDetails];

XCTAssert([fileExtPredicate02 evaluateWithObject:searchStr]);

---

更新

为了同时获得 ID 和 NAME，我使用了。

NSArray * StudentIDs = [NSArray arrayWithObjects:@"07bg1234",@"07ac1234", nil];
NSArray * StudentNames = [NSArray arrayWithObjects:@"aaaaaaa",@"bbbbb", nil];
NSDictionary * StudentDetails = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:StudentIDs,StudentNames, nil] forKeys:[NSArray arrayWithObjects:@"ID",@"NAME", nil]];

NSPredicate * fileExtPredicate02 = [NSPredicate predicateWithFormat:@"SELF IN %@.ID OR SELF IN %@.NAME", StudentDetails, StudentDetails];

XCTAssert([fileExtPredicate02 evaluateWithObject:@"07bg1234"]);
XCTAssert([fileExtPredicate02 evaluateWithObject:@"aaaaaaa"]);

这对我来说感觉很笨拙，我认为使用 SUBQUERY() 会有更好的答案，但我必须再考虑一下。

---

更新 2

因此，如果您能忍受一些不稳定，这里是SUBQUERY() 版本。谓词是SUBQUERY(%@, $value, SELF IN $value).@count > 0。 SUBQUERY(%@, $value, SELF IN $value) 返回一个匹配值数组，.@count > 0 如果至少有 1 个匹配则返回 true。与之前的示例不同，我没有通过StudentDetails。我需要通过StudentDetails.allValues。

NSArray * StudentIDs = [NSArray arrayWithObjects:@"07bg1234",@"07ac1234", nil];
NSArray * StudentNames = [NSArray arrayWithObjects:@"aaaaaaa",@"bbbbb", nil];
NSDictionary * StudentDetails = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:StudentIDs,StudentNames, nil] forKeys:[NSArray arrayWithObjects:@"ID",@"NAME", nil]];

NSPredicate * fileExtPredicate02 = [NSPredicate predicateWithFormat:@"SUBQUERY(%@, $value, SELF IN $value).@count > 0", StudentDetails.allValues];

XCTAssert([fileExtPredicate02 evaluateWithObject:@"07bg1234"]);
XCTAssert([fileExtPredicate02 evaluateWithObject:@"aaaaaaa"]);

Answer 2

对于字典，您需要条件 <Item> IN <Key> 对应于您的示例中的 @"07bg1234" IN @"ID"。 evaluateWithObject 中的对象是字典。

NSPredicate *fileExtPredicate02 = [NSPredicate predicateWithFormat:@"%@ IN ID", searchStr];
if ([fileExtPredicate02 evaluateWithObject: studentDetails] == YES) {
  NSLog(@"Student Details: %@ Exists",searchStr);
}
else {
  NSLog(@"Student Details: %@ not Exists", searchStr);
};