- [__ NSCFDictionary objectAtIndex：]：無法識別的選擇發送到實例

Question

這裏是我的代碼：

NSString *url = @"https://www.googleapis.com/language/translate/v2?key=API&q=hello%20world&source=en&target=de"; 
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]]; 
NSLog(@"%@",request); 

NSData *response = [NSURLConnection sendSynchronousRequest:request 
              returningResponse:nil 
                 error:nil]; 
NSLog(@"%@",response); 
NSError *jsonParsingError = nil; 
NSArray *retrievedJTrans = [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError]; 
NSLog(@"%@",retrievedJTrans); 
NSDictionary *translation; 
for(int i=0; i<[retrievedJTrans count];i++) 
{ 
    translation=[retrievedJTrans objectAtIndex:i]; 
    NSLog(@"Statuses: %@", [translation objectForKey:@"translatedText"]); 
} 
NSLog(@"%@",[translation class]); 

我試圖找回從這個簡單的JSON譯文：

{ 
    "data": { 
     "translations": [ 
      { 
       "translatedText": "Hallo Welt" 
      } 
     ] 
    } 
} 

但我得到的錯誤：

-[__NSCFDictionary objectAtIndex:]: unrecognized selector sent to instance 

任何幫助表示讚賞。使用最新的Xcode。

Answer 1

NSArray *retrievedJTrans = [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError]; 

是一本字典

你可能想要什麼

NSDictionary *retrievedJTransD = [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError]; 
NSArray *retrievedJTrans = retrievedJTransD[@"data"][@"translations"]; 

Answer 2

看到這一行：

NSArray *retrievedJTrans = [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError]; 

你假設JSON返回給你的是一個數組，但錯誤信息告訴你，這是一個NSDictionary。一個小測試，你可以使用方法是：

id receivedObject = [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError]; 
if ([receivedObject isKindOfClass:[NSDictionary class]]) { 
    // Process the object as a dictionary 
} else { 
    // Process the object as an array 
}