NSInvalidArgumentException'，原因：'-[__NSCFConstantString objectForKey:]：无法识别的选择器发送到实例 0x10256a1b0'

Question

我有一个视图控制器，我在其中解析 xml 文件并在字典中获取其值，我试图获取标签中的值，但我的应用程序因显示此错误而崩溃*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFConstantString objectForKey:]: unrecognized selector sent to instance 0x10256a1b0'

我从字典中获取值的代码是这些，

 NSLog(@"string: %@", str);
NSDictionary *xmlDoc = [NSDictionary dictionaryWithXMLString:str];
NSLog(@"dictionary: %@", xmlDoc);

for (NSDictionary * oneCustomer in xmlDoc)
{
    // Create a new Customer record

    _lblID.text = [oneCustomer objectForKey:@"_id"];
    NSLog(@"Reg: %@ ",_lblID.text);

    _lblAlert.text = [oneCustomer objectForKey:@"_topic"];
    NSLog(@"Make: %@ ",_lblAlert.text);

    _lblxref.text = [oneCustomer objectForKey:@"xref"];

    NSLog(@"Type: %@ ",_lblxref.text);

    _lbltext.text = [oneCustomer objectForKey:@"text"];
    NSLog(@"Model: %@ ", _lbltext.text);

    _lblgraphic.text = [oneCustomer objectForKey:@"explanation"];
    NSLog(@"Model: %@ ",_lblgraphic.text);

    _lblprompt.text = [oneCustomer objectForKey:@"prompt"];
    NSLog(@"Model: %@ ",_lblprompt.text);

   _lblvoice.text = [oneCustomer objectForKey:@"_id"];
    NSLog(@"Model: %@ ", _lblvoice.text);

    //roils = [oneCustomer objectForKey:@"recommended oil"];
    //NSLog(@"Model: %@ ",roils);
}

如何消除此错误？ 这是我的字典，

dictionary: {
"__name" = QF;
"_category" = "C&M";
"_id" = AB2001;
"_ni_exempt" = no;
"_topic" = Alertness;
answers =     {
    answer =         (
                    {
            "_correct" = no;
            text = "give an arm signal as well as using your indicators";
        },
                    {
            "_correct" = no;
            text = "signal so that other drivers can slow down for you";
        },
                    {
            "_correct" = yes;
            text = "look over your shoulder for a final check";
        },
                    {
            "_correct" = no;
            text = "select a higher gear than normal";
        }
    );
};
question =     {
    explanation =         {
        text = "If you want to make a U-turn, slow down and ensure that the road is clear in both directions. Make sure that the road is wide enough to carry out the manoeuvre safely.";
        voice =             {
            "_id" = "AB2001-2";
        };
    };
    prompt = "Mark one answer";
    text = "Before you make a U-turn in the road, you should";
    voice =         {
        "_id" = "AB2001-1";
    };
    xref = "DES s4, DES s9, HC r159-161";
};

我必须从这本字典中提取所有值我怎样才能得到这个？

Answer 1

希望对你有帮助，

-(void)fetchValuesFromDictioanry:(NSDictionary*)xmlDict
{
    for (NSString *string in [xmlDict allKeys])
    {
        if ([[xmlDict valueForKey:string] isKindOfClass:[NSDictionary class]])
        {
            [self fetchValuesFromDictioanry:[xmlDict valueForKey:string]];
        }
        else if ([[xmlDict valueForKey:string] isKindOfClass:[NSString class]])
        {

            if ([string isEqualToString:@"_id"] && [[xmlDict valueForKey:string] isKindOfClass:[NSString class]])
            {
                _lblID.text = [xmlDict valueForKey:@"_id"];
            }
            else
           {
               NSLog(@"%@", NSStringFromClass([[xmlDict valueForKey:string] class]));
           }
            NSLog(@"Model: %@ ", [xmlDict valueForKey:string]);

          //Set here other labels
        }
        else if ([[xmlDict valueForKey:string] isKindOfClass:[NSArray class]])
        {
            for (NSDictionary *dictionary in [xmlDict valueForKey:string]) {

                [self fetchValuesFromDictioanry:dictionary];
            }
        }
    }
}

你可以这样调用，

[self fetchValuesFromDictioanry:xmlDoc];