Question

所以我有一个NSDictionary，其中包含各种数据。打印到日志时，它打印如下：

[{"user_id":3016817,"grade":"A","percent":"93","grading_periods":[{"assignments":[{"points":100.0,"grade":"A","score":95.0,"percent":"93","comment":null,"id":3268180},{"points":100.0,"grade":"A","score":90.0,"percent":"93","comment":null,"id":3268181}],"grade":"A","percent":"93","name":"Default"}]},{"user_id":3016818,"grade":"A","percent":"94","grading_periods":[{"assignments":[{"points":100.0,"grade":"A","score":92.0,"percent":"94","comment":null,"id":3268180},{"points":100.0,"grade":"A","score":95.0,"percent":"94","comment":null,"id":3268181}],"grade":"A","percent":"94","name":"Default"}]}]

如果我在线使用格式化程序，它的可读性更高，看起来像这样：

[
{
    "user_id": 3016817, 
    "grade": "A", 
    "percent": "93", 
    "grading_periods": [
        {
            "assignments": [
                {
                    "points": 100, 
                    "grade": "A", 
                    "score": 95, 
                    "percent": "93", 
                    "comment": null, 
                    "id": 3268180
                }, 
                {
                    "points": 100, 
                    "grade": "A", 
                    "score": 90, 
                    "percent": "93", 
                    "comment": null, 
                    "id": 3268181
                }
            ], 
            "grade": "A", 
            "percent": "93", 
            "name": "Default"
        }
    ]
}, 
{
    "user_id": 3016818, 
    "grade": "A", 
    "percent": "94", 
    "grading_periods": [
        {
            "assignments": [
                {
                    "points": 100, 
                    "grade": "A", 
                    "score": 92, 
                    "percent": "94", 
                    "comment": null, 
                    "id": 3268180
                }, 
                {
                    "points": 100, 
                    "grade": "A", 
                    "score": 95, 
                    "percent": "94", 
                    "comment": null, 
                    "id": 3268181
                }
            ], 
            "grade": "A", 
            "percent": "94", 
            "name": "Default"
        }
    ]
}
]

我的问题是如何使用此词典访问特定user_id的成绩或分数值？

Answer 1

您的字符串代表name,tags,time,mean server_1,a,2015-10-24T11:45:27.869918Z,620023.5521262008 server_2,b,2015-10-24T11:45:27.869918Z,0 server_3,c,2015-10-24T11:45:27.869918Z,0 server_4,d,2015-10-24T11:45:27.869918Z,66.16323731138544，而不是NSArray。它是一个JSON字符串，因此您可以使用NSDictionary解析它：

NSJSONSerialization

Answer 2

执行此操作的简单方法是

for (NSDictionary* d in theArray) {
    if ([d[@"user_id"] isEqualToString: u]) {
        // do something
    }
}

马特是对的，它是一系列词典，无论你声称是什么类型。

Answer 3

您可以使用NSJsonSerialization类的以下类方法来创建包含所有字典的NSArray。 +（id）JSONObjectWithData：（NSData *）数据选项：（NSJSONReadingOptions）opt error：（NSError **）error;

从JSON获得字典数组后，您可以执行以下操作：

NSArray *filteredjsonArr = [jsonArr filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"user_id == %@", @"3016818"]];
NSDictionary *dict = [filtered firstObject];
if (dict != nil) {
   NSString *grade = [dict objectForKey:@"grade"];
   NSArray *gradingPeriods = [dict objectForKey:@"grading_periods"];
}

要访问特定作业的分数和成绩，您需要深入了解gradingPeriods数组。

从NSDictionary中提取数据

3 个答案: