目標C-嘗試決議json和構建模型的問題

大家好，我在 * OBJECTIVE C * 方面需要幫助 * 我是 Objc 的新手——但不是很快。但我發現自己在簡單的 json 決議和構建模型上苦苦掙扎。

這是我要決議的模型的示例。

{
"success": true,
"data": {
    "memes": [
        {
            "id": "61579",
            "name": "One Does Not Simply",
            "url": "https://i.imgflip.com/1bij.jpg",
            "width": 568,
            "height": 335,
            "box_count": 2
        },
        {
            "id": "101470",
            "name": "Ancient Aliens",
            "url": "https://i.imgflip.com/26am.jpg",
            "width": 500,
            "height": 437,
            "box_count": 2
        }
        // probably a lot more memes here..
    ]
}

}

我想為這個 json 物件創建一個“MemeModel”。并在我的 viewController 上決議它，然后添加到我的 dataSource 陣列中......誰能解釋我或告訴我應該如何完成......所有舊的 objc 谷歌搜索都沒有幫助我。謝謝你！

QTMeme.h 檔案

@interface QTMeme : NSObject

@property (nonatomic,strong) QTData *data;

@end

@interface QTData : NSObject

@property (nonatomic,copy) NSMutableArray<QTMemeResponse *> *memes;

@end

@interface QTMemeResponse : NSObject

@property (nonatomic,copy) NSString *url;
@property (nonatomic,copy) NSString *name;

-(instancetype) initMemesWithImage:(NSString *)url withTitle:(NSString *)name;

@end

這是 QTMeme.m 檔案..

    @implementation QTMeme
@end

@implementation QTData
@end

@implementation QTMemeResponse

-(instancetype) initMemesWithImage:(NSString *)url withTitle:(NSString *)name {
    self = [super init];
    
    if (self) {
        self.url = url;
        self.name = name;
    }
    return self;
}

@end

uj5u.com熱心網友回復：

首先，讓我們重命名您的類，它們具有誤導性：

QTMeme -> QTMemeResponse
QTData -> QTMemeResponseData
QTMemeResponse -> QTMeme

現在，由于我們解碼物件字典，讓我們initWithJSONDictionary:為每個物件添加一個方法。

@interface QTMeme : NSObject
@property (nonatomic,copy) NSString *url;
@property (nonatomic,copy) NSString *name;
-(instancetype)initWithJSONDictionary:(NSDictionary *)dict;
-(instancetype) initMemesWithImage:(NSString *)url withTitle:(NSString *)name;
@end

@interface QTMemeResponseData : NSObject
@property (nonatomic,copy) NSMutableArray<QTMeme *> *memes;
-(instancetype)initWithJSONDictionary:(NSDictionary *)dict;
@end

@interface QTMemeResponse : NSObject
@property (nonatomic,strong) QTMemeResponseData *data;
-(instancetype)initWithJSONDictionary:(NSDictionary *)dict;
@end

執行：

@implementation QTMemeResponse
-(instancetype)initWithJSONDictionary:(NSDictionary *)dict {
    self = [super init];
    if (self) {
        self.data = [[QTMemeResponseData alloc] initWithJSONDictionary:dict[@"data"]];
    }
    return self;
}
@end

@implementation QTMemeResponseData
-(instancetype)initWithJSONDictionary:(NSDictionary *)dict {
    self = [super init];
    if (self) {
        NSArray *jsonDicts = dict[@"memes"];
        _memes = [[NSMutableArray alloc] init];
        for (NSDictionary *aJSONDict in jsonDicts) {
            QTMeme *aMeme = [[QTMeme alloc] initWithJSONDictionary:aJSONDict];
            [_memes addObject:aMeme];
        }
    }
    return self;
}
@end

@implementation QTMeme

-(instancetype)initWithJSONDictionary:(NSDictionary *)dict {
    return [self initMemesWithImage:dict[@"name"] withTitle:dict[@"url"]];
}
-(instancetype) initMemesWithImage:(NSString *)url withTitle:(NSString *)name {
    self = [super init];

    if (self) {
        self.url = url;
        self.name = name;
    }
    return self;
}

@end

解碼：

NSError *decodingError = nil;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data
                                                     options:kNilOptions
                                                       error:&decodingError];

if (decodingError) {
    NSLog(@"Error while decoding JSON: %@ with stringified data: %@", decodingError, [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
} else {
    QTMemeResponse *decoded = [[QTMemeResponse alloc] initWithJSONDictionary:json];
    NSLog(@"decoded: %@", decoded);
}

輸出：

$>decoded: <QTMemeResponse: 0x600001764810>

您可以在除錯器中看到這些值，但也許讓我們通過覆寫添加一些有用的日志description：

對于QTMemeResponse：

-(NSString *)description {
    return [NSString stringWithFormat:@"%@ data: %@", [super description], self.data];
}

對于QTMemeResponseData：

-(NSString *)description {
    return [NSString stringWithFormat:@"%@ memes: %@", [super description], self.memes];
}

對于QTMeme：

-(NSString *)description {
    return [NSString stringWithFormat:@"%@ name: %@, url: %@", [super description], self.name, self.url];
}

現在輸出：

$>decoded: <QTMemeResponse: 0x600001764810> data: <QTMemeResponseData: 0x6000017648b0> memes: (
    "<QTMeme: 0x6000015300e0> name: https://i.imgflip.com/1bij.jpg, url: One Does Not Simply",
    "<QTMeme: 0x600001530100> name: https://i.imgflip.com/26am.jpg, url: Ancient Aliens"
)

請注意，在Codable使用(NS)JSONSerialization. 當然， for 回圈可能是 a compactMap()，您需要做很多as? [String: Any]，等等，但這是相同的想法......

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