在 iOS 中使用数组解析 JSON 时出错

Posted 2023-03-15

【中文标题】在 iOS 中使用数组解析 JSON 时出错

【英文标题】：Getting error in JSON parsing with array in iOS

【发布时间】：2015-06-16 06:10:56

【问题描述】：

我是 iPhone 的新手，基本上在我的应用程序中我正在解析 JSON 模型，需要将其保存在我的自定义实体类中。

JSON 模型：

    "Products": [
        
            "Pcs": [
                
                    "product_id": 2,
                    "product_name": "MyProduct",
                    "category": 
                        "Clamshells": [
                            
                                "product_category_id": 11,
                                "product_category_name": "MyProductCategory",
                                "Sub_category": [
                                    
                                        "sub_category_id": 21,
                                        "sub_category_name": "MyProductSubCategory"
                                    
                                ]
                            
                        ],
                        "Detachables": [
                            
                                "product_category_id": 12,
                                "product_category_name": "MyProductCatrgory1",
                                "Sub_category": [
                                    
                                        "sub_category_id": 31,
                                        "sub_category_name": "MyProductSubCategory1"
                                    
                                ]
                            
                        ],
                        "Convertibles": [
                            
                                "product_category_id": 13,
                                "product_category_name": "MyProductCatrgory2",
                                "Sub_category": [
                                    
                                        "sub_category_id": 41,
                                        "sub_category_name": "MyProductSubCategory2"
                                    
                                ]
                            
                        ]
                    
                
            ]
        
    ]

我创建了三个实体类，例如：

PCs.h：

#import <Foundation/Foundation.h>
#import "MyProductCategory.h"

@interface PCs : NSObject

@property (nonatomic, retain) NSString *productTitle;
@property (nonatomic, retain) NSString *productId;
@property (nonatomic, retain) MyProductCategory *myProductCategory;

@end

MyProductCategory.h：

#import <Foundation/Foundation.h>
#import "Clamshell.h"

@interface MyProductCategory : NSObject

@property (nonatomic, retain) Clamshell *clamshell;
@property (nonatomic, retain) NSMutableArray *arrayClamshells;
@property (nonatomic, retain) NSMutableArray *arrayConvertibles;
@property (nonatomic, retain) NSMutableArray *arrayDetachables;

@end

翻盖.h：

#import <Foundation/Foundation.h>

@interface Clamshell : NSObject<NSCoding>

@property (nonatomic, retain) NSString *subProductTitle;
@property (nonatomic, retain) NSString *subProductId;

@end

这是我解析数据的代码：

    NSDictionary* json = [NSJSONSerialization JSONObjectWithData:responseData
                                                                     options:kNilOptions
                                                                       error:&error];


                productsDict = [json objectForKey:@"Products"];

                pcsArray = [[NSMutableArray alloc] init];

    dispatch_async (dispatch_get_main_queue (),
                            ^
                                for (NSDictionary *items in productsDict)
                                
                                    NSDictionary *pcsDict = [items objectForKey:@"Pcs"];

                                    for (NSDictionary *item1 in pcsDict) 

                                        PCs *pcs = [[PCs alloc] init];
                                        pcs.productId = [item1 objectForKey:@"product_id"];
                                        pcs.productTitle = [item1 objectForKey:@"product_name"];

                                        //for the category                                            
                                           pcs.myProductCategory = [[MyProductCategory alloc] init];
                                           pcs.myProductCategory = [item1 objectForKey:@"category"];

                                           NSMutableArray *clamshellDict = [pcs.myProductCategory valueForKey:@"Clamshells"];


                                           NSMutableArray *array = [[NSMutableArray alloc]init];

                                            for (NSDictionary *items2 in clamshellDict) 
                                                Clamshell *clam = [[Clamshell alloc] init];
                                                clam.subProductId = [items2 objectForKey:@"sub_category_id"];
                                                clam.subProductTitle = [items2 objectForKey:@"sub_category_name"];

                                                [array addObject:clam];// 
                                            

                                            pcs.myProductCategory.arrayClamshells = [NSMutableArray alloc] init]; //here it is crashing

pcs.myProductCategory.arrayClamshells = [array copy];
                                        

                                        [pcsArray addObject:pcs];
                                    

                                    NSLog(@"PCs array is = %@", pcsArray);
                                

                            );

但是当我初始化数组或为其设置任何值时它会崩溃。 错误信息是：

-[__NSCFDictionary setArrayClamshells:]: unrecognized selector sent to instance 0x7f8f16059730

 Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary setArrayClamshells:]: unrecognized selector sent to instance 0x7f8f16059730'

【问题讨论】：

setArrayClamshells 方法在哪里？

@iDev 只是.arrayClamshells =时调用的默认setter方法。

是的，它看起来像 object.array 或 object setArray

在 arrayClamshells 属性中保留一个断点。尝试使用异常断点

您的问题似乎存在：pcs.myProductCategory = [item1 objectForKey:@"category"];。您将 NSDictionary 分配给 MyProductCategory，然后将其视为 NSDictionary（为什么会导致并解释崩溃错误）。另外，还有一些 alloc/init 显然做得不好。

【参考方案1】：

你的代码在这里

pcs.myProductCategory = [[MyProductCategory alloc] init];
pcs.myProductCategory = [item1 objectForKey:@"category"];

正在正确创建您的 MyProductCategory 实例，但随后将其替换为字典。您可能打算将第二行写为

NSDictionary *category = [item1 objectForKey:@"category"];

然后在下一行使用它来解压字典内容

【讨论】：

感谢@Wain 的回答。

【参考方案2】：

错误是您有一行正确地将myProductCategory 初始化为您的自定义对象：

pcs.myProductCategory = [[MyProductCategory alloc] init];

但是在下一行中，您将其丢弃并将其设置为category 条目指定的字典：

pcs.myProductCategory = [item1 objectForKey:@"category"];

因此，当您到达以下行时，它会崩溃，因为myProductCategory 不再是MyProductCategory，而是NSDictionary：

pcs.myProductCategory.arrayClamshells = [NSMutableArray alloc] init];