[英]How to declare optional property in Mantle?
具体情况详情:
在我目前的照片应用程序中,存在这样的情况:首先允许用户体验而不登录,但是在后端响应的JSON中没有一些字段(例如:投票,购买等)。 如果用户已登录,则该字段将以JSON格式添加。
我将展示我的工具细节如下:
PhotoListResponseModel(直接继承MTLModel)
@interface PhotoListResponseModel : MTLModel <MTLJSONSerializing>
...
@property (nonatomic, copy, readonly) NSNumber *foo;
@property (nonatomic, copy, readonly) NSArray<PhotoModel *> *subPhotos;
@end
@interface PhotoModel : MTLModel <MTLJSONSerializing>
@property (nonatomic, copy, readonly) NSNumber *photoID;
@property (nonatomic, copy, readonly) NSURL *imageUrl;
...
@end
@implementation PhotoListResponseModel
+ (NSDictionary *)JSONKeyPathsByPropertyKey {
return @{@"foo": @"foo"
@"subPhotos": @"photos"
};
}
+ (NSValueTransformer *)subPhotosJSONTransformer {
return [MTLJSONAdapter arrayTransformerWithModelClass:PhotoModel.class];
}
@end
@implementation PhotoModel
+ (NSDictionary *)JSONKeyPathsByPropertyKey {
return @{
@"photoID": @"id",
@"userID": @"user_id",
};
}
@end
相应地, JSON示例如下:
noAuthPhoto.json
{
"foo": 1,
"photos": [
{
"id": 204748881,
"image_url": "https://foo1/bar1",
},
{
"id": 204996257,
"image_url": "https://foo2/bar2"
}
],
…
…
}
AuthedPhoto.json
{
"foo": 1,
"photos": [
{
"id": 204748881,
"image_url": "https://foo1/bar2”,
"voted": false,
"purchased": false
},
{
"id": 204996257,
"image_url": "https://foo2/bar2”,
"voted": false,
"purchased": false
}
],
...
...
}
那么, 新字段如何兼容我现有的代码呢?
可选物业? (我不知道该怎么做。)
或者从PhotoListResponseModel和PhotoModel添加继承的子类?
或者任何好主意:)
更新:我注意到了这些信息 ,但仍然不知道该怎么做。
可选属性仅在Swift中可用,但Obj-C的类似想法 - 具有可能的nil
值的对象 - 应该可以正常工作。 您可以将以下NSNumber
属性添加到您的PhotoModel
:
@property (nonatomic, strong) NSNumber *voted;
@property (nonatomic, strong) NSNumber *purchased;
并在PhotoModel
对象创建期间从解析的JSON中分配您的BOOL值,如下所示:
photoModelObject.voted = [NSNumber numberWithBool:[parsedJson valueForKey:@"voted"]];
photoModelObject.purchased = [NSNumber numberWithBool:[parsedJson valueForKey:@"purchased"]];
接下来,当您引用照片对象时,只需检查这些属性是否nil
值。 如果是 - 您的用户未登录,您不需要显示它们。 否则,从它们中提取BOOL值,如下所示:
if (photoModelObject.voted && photoMobelObject.purchased) {
BOOL isVoted = [photoModelObject.voted boolValue];
BOOL isPurchased = [photoModelObject.purchased boolValue];
// Use booleans to present info for registered users
} else {
// There is no info about votes and purchasing provided for the current user
}
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