iPhone上的JSON数据问题

我从JSON web服务获取这些数据

[{"identity":"DEMO","assets":[{"identity":"34DL3611","systemId":"544507"},{"identity":"34GF0512","systemId":"5290211"},{"identity":"34HH1734","systemId":"111463609"},{"identity":"34HH1736","systemId":"111463622"},{"identity":"34YCJ15","systemId":"294151155"}],"systemId":4921244}]

我使用此方法获取标识的资产值（“资产”：[{“标识”：“34DL3611”，“系统ID”：“544507”}）：

vehicleList=[dict objectForKey:@“资产”]；
self.listVehicles=[[NSMutableArray alloc]init]；
对于（整数索引=0；索引<[vehicleList count]；索引++）{
itemDict=[车辆列表对象索引：索引]；
[self.listVehicles addObject:[itemDict objectForKey:@“identity”]；
}

如何获取systemId值

我已经为systemId试过了

vehicleListID = [dict objectForKey:@"systemId"];

    self.listVehiclesID =[[NSMutableArray alloc]init];

for (NSUInteger index = 0; index < [vehicleListID count]; index++) {

    assetsIdDict = [vehicleListID objectAtIndex: index];

    [self.listVehiclesID addObject:[assetsIdDict objectForKey:@"systemId"]];
}

vehicleListID=[dict objectForKey:@“systemId]”；
self.listVehiclesID=[[NSMutableArray alloc]init]；
对于（整数索引=0；索引<[vehicleListID计数]；索引++）{
assetsIdDict=[vehicleListID对象索引：索引]；
[self.listVehiclesID addObject:[assetsIdDict objectForKey:@“systemId]”；
}

---

但获取错误：[uuuu NSCFNumber count]：无法识别的选择器发送到实例0x784c730

您基本上就快到了。您可能只是想要这样：

NSString *systemId = [itemDict objectForKey:@"systemId"];

关于此代码，您有：

vehicleListID = [dict objectForKey:@"systemId"];

    self.listVehiclesID =[[NSMutableArray alloc]init];

for (NSUInteger index = 0; index < [vehicleListID count]; index++) {

    assetsIdDict = [vehicleListID objectAtIndex: index];

    [self.listVehiclesID addObject:[assetsIdDict objectForKey:@"systemId"]];
}

---

然后对所有这些对象执行任何操作。

您得到的json响应是一个数组。vehicleList应该是json响应的objectatIndex 0

    NSDictionary  *vehicleList = [[arrayLoadedFromJson objectAtIndex:0] objectForKey: @"assets"];


vehicleList = [dict objectForKey: @"assets"];

    self.listVehicles = [[NSMutableArray alloc] init];

for (NSUInteger index = 0; index < [vehicleList count]; index++) {

    itemDict = [vehicleList objectAtIndex: index];

    [self.listVehicles addObject:[itemDict objectForKey:@"identity"]];

    [self.listVehicles addObject:[itemDict objectForKey:@"systemId"]];

}

---

要在单独的数组中使用，需要初始化新的NSMutableArray并添加对象

---

否则，更好的方法是，声明一个包含2个NSString成员的新类，例如，

identity

和

systemId

。从JSON中提取值并分配给类成员。然后将该对象添加到数组中。

同样的方法。

[itemDict objectForKey:@“systemId”]

。要在数组中进行此操作，您需要初始化新的NSMUTABLEARRY。我尝试了此操作，但给出了错误：[\uu NSCFNumber count]：发送到实例0x784c730的无法识别的选择器

NSNumber *outerIdentity = [dict objectForKey:@"identity"];
NSNumber *outerSystemId = [dict objectForKey:@"systemId"];
NSArray *vehicleList = [dict objectForKey:@"assets"];
for (NSUInteger index = 0; index < [vehicleList count]; index++) {
    NSDictionary *itemDict = [vehicleList objectAtIndex: index];
    NSString *identity = [itemDict objectForKey:@"identity"];
    NSString *systemId = [itemDict objectForKey:@"systemId"];
}

    NSDictionary  *vehicleList = [[arrayLoadedFromJson objectAtIndex:0] objectForKey: @"assets"];


vehicleList = [dict objectForKey: @"assets"];

    self.listVehicles = [[NSMutableArray alloc] init];

for (NSUInteger index = 0; index < [vehicleList count]; index++) {

    itemDict = [vehicleList objectAtIndex: index];

    [self.listVehicles addObject:[itemDict objectForKey:@"identity"]];

    [self.listVehicles addObject:[itemDict objectForKey:@"systemId"]];

}

  [self.listVehicles addObject:[itemDict objectForKey:@"systemId"]];