Question

我是iOS开发的新手，我的问题是当我解析数据时，只显示上面显示的值的上一个值没有显示。请解决我的问题。数组名称city info获取3个值，但是当我想显示它们时，它给出了数组的最后一个值。

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:WebData1 options:0 error:0];
    NSArray *city_info = [json objectForKey:@"city_info"];
    for(NSDictionary *dic in city_info) {
        NSMutableArray *vlcc_service_name = [dic objectForKey:@"vlcc_service_name"];

        Centers = [[NSMutableArray alloc]initWithObjects:vlcc_service_name, nil];
    }
    // NSLog(@"%@", vlcc_service_name);
    NSLog(@"%@", Centers);
    [_CenterTableView reloadData];
}

Answer 1

NSDictionaries是无序的，没有第一个或最后一个元素。实际上，即使在特定字典的生命周期内，密钥的顺序也永远不会保证是相同的。

如果您想要任何对象，可以获得其中一个键：

var country = "Please click on a country";

function setCountry(event) {
    country = this.id;
    return false;
}

function search_track() {
    // do something with country, such as:
    alert(country);
}

document.getElementById("canada").addEventListener("click", setCountry, false);
document.getElementById("usa").addEventListener("click", setCountry, false);
document.getElementById("search_track").addEventListener("click", search_track, false);

选择 - 2

数组你可以获得所有对象

id key = [[json allKeys] objectAtIndex:0]; // ensure that your 'json' is not empty
id object = [json objectForKey:key];

Answer 2

 Centers = [NSMutableArray new]; // allocate the memory on outside the Loop
for(NSDictionary *dic in city_info) {

    [Centers addObject: [dic objectForKey:@"vlcc_service_name"]];
}

 NSLog(@"the last object=%@", [Centers lastObject]);
// else
  NSLog(@"the last object=%@", [yourArray objectAtIndex:[Centers count] - 1]; );

Answer 3

您可以在没有任何for loop的情况下执行此操作。这样做： NSMutableArray *Centers = [[NSMutableArray alloc]initwithArray:city_info];

Answer 4

请试试这个。

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:WebData1 options:0 error:0];
    NSArray *city_info = [json objectForKey:@"city_info"];
    NSMutableArray  *Centers = [[NSMutableArray alloc]init];
  for(NSDictionary *dic in city_info) {
    NSString *vlcc_service_name = [dic objectForKey:@"vlcc_service_name"];
   /NSLog(@"%@", vlcc_service_name);
    [Centers addObject: vlcc_service_name];
  }

NSLog(@"%@", Centers);
[_CenterTableView reloadData];
}

只获得最后一本字典

4 个答案: