Question

我目前正在尝试解析此JSON

[{"id":"1","dish_name":"Pasta & ketchup","category":"main","rating":"5","rating_count":null,"author":"Me","ingredients":"Pasta\nKetchup\nWater","description":"Very good for students\nCheap too!","picture":null,"protein":"7","fat":"11","carbs":"12","calories":"244","developer_lock":"1"},{"id":"2","dish_name":"Pasta & Kødsovs","category":"main","rating":"5","rating_count":null,"author":"Me","ingredients":"Pasta\nKødsovs\nWater","description":"Very good for students\nCheap too!","picture":null,"protein":"7","fat":"11","carbs":"12","calories":"244","developer_lock":"1"}]

但它失败并且崩溃了这段代码

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [connection release];
    NSError *error = NULL;

    NSDictionary* json = [NSJSONSerialization
                      JSONObjectWithData:responseData
                      options:kNilOptions
                      error:&error];
    recipes = [[NSArray alloc] initWithArray:[json objectForKey:@"dish_name"]];
    [uit reloadData];
}

有人有任何线索，为什么它会因错误-[__NSCFArray objectForKey:]: unrecognized selector sent to instance 0x8077240而崩溃？

提前致谢。

Answer 1

以[__NSCFArray objectForKey:]开头的错误消息表示您有一个NSArray（JSON的根对象是一个数组 - 注意开始和结束方括号），并且您试图将其视为字典。总而言之，

recipes = [[NSArray alloc] initWithObject:[json objectForKey:@"dish_name"]];

应该是

recipes = [[NSArray alloc] initWithObject:[[json objectAtIndex:0] objectForKey:@"dish_name"]];

请注意，数组中有两个对象，因此您可能也想使用[json objectAtIndex:1]。

编辑：如果你有动态的食谱数量，你可以这样做：

recipes = [[NSMutableArray alloc] init];
for (NSDictionary *dict in json) {
    [recipes addObject:[dict objectForKey:@"dish_name"]];
}

Answer 2

如果您的json NSDictionary是真实的＆amp;有效的NSDictionary对象，您对此的调用：

[json objectForKey:@"dish_name"]

应该正确地返回：

"Pasta & ketchup"

肯定不是数组。它是一个NSString对象。

这就是为什么对“initWithArray”的召唤是轰炸的原因。

JSON在iOS上无法正常工作

2 个答案: