ios - Objective-C - 读取 JSON key 时的问题

Question

大家好，我正在使用 JSON file在我的 xCode 项目中。

我可以轻松显示各种JSON键，但是当我调用一个键时，它指定我的应用程序崩溃，我不明白为什么......

我非常小心地正确编写了 key ，但它一直在崩溃......

这是我的例子JSON file

{
  "Università" : {
    "uniID" : {
      "latitudine" : 43.115441,
      "longitudine" : 12.389587,
      "nome" : "Università per stranieri di Perugia",
      "regione" : "Umbria"
    },
    "uniID" : {
      "latitudine" : 41.860348,
      "longitudine" : 12.496308,
      "nome" : "Università degli Studi Internazionali di Roma ( UNINT )",
      "regione" : "Lazio"
    },
}
}

当我尝试恢复 “姓名” 关键我的应用程序崩溃了，即使我调用 也是如此“纬度” 或 "经度" ETC ...

我在哪里做错了？

这些是我用来读取 JSON 文件的函数

-(void)setupUniversityLocation:(MKMapView *)mapView {

    NSDictionary *dict = [self JSONUniversity];
    NSArray *universityArray = [[dict objectForKey:@"Università"] objectForKey:@"uniID"];

       for (NSDictionary *uni in universityArray) {

           NSString *uniname = [uni objectForKey:@"nome"];
           NSLog(@"uniname  %@",uniname);
 }
}

#pragma mark - Read JSON Data University

-(NSDictionary *)JSONUniversity {
    NSString *path = [[NSBundle mainBundle] pathForResource:@"university" ofType:@"json"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    return [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
}

我也想问你如何直接读取 key “姓名” , “纬度” 等等...没有在哪里调用 "uniID" key ？是否可以绕过类别键？

Answer 1

您的 json 文件中没有数组。您应该将 json 文件更改为

{
    "Università" : [
        {
            "latitudine" : 43.115441,
            "longitudine" : 12.389587,
            "nome" : "Università per stranieri di Perugia",
            "regione" : "Umbria"
        },
        {
            "latitudine" : 41.860348,
            "longitudine" : 12.496308,
            "nome" : "Università degli Studi Internazionali di Roma ( UNINT )",
            "regione" : "Lazio"
        }
    ]
}

使用 []显示数组而不是 {}下面的代码将起作用

-(void)setupUniversityLocation:(MKMapView *)mapView {

    NSDictionary *dict = [self JSONUniversity];
    NSArray *universityArray = [dict objectForKey:@"Università"];

    for (NSDictionary *uni in universityArray) {
        NSString *uniname = [uni objectForKey:@"nome"];
        NSLog(@"uniname  %@",uniname);
    }
}

#pragma mark - Read JSON Data University

-(NSDictionary *)JSONUniversity {
    NSString *path = [[NSBundle mainBundle] pathForResource:@"university" ofType:@"json"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    return [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
}