如何在GET請求之外使用變量？

Question

我想：

• 一個GET請求（AFNetworking）
• 分配給請求成功
• 使用變量一旦請求完成內部變量初始化變量之前

---

我得到的錯誤：

• 當試圖GET請求之後做一些變量，它打破了，自稱有給變量沒有值尚未

---

以下是我的代碼，我該如何解決這個問題問題？

- (IBAction)synchronisePressed { 
    //Would like to initialise a variable here 
    __block NSArray *received; 
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager]; 
    [manager GET:@"http://foo.com/foo/" 
     parameters:nil 
      success:^(AFHTTPRequestOperation *operation, id responseObject) { 
       //Assign responseObject to received object 
       received = responseObject; 
       NSLog(@"Woo: %@", @"got here"); 
      } 

      failure:^(AFHTTPRequestOperation *operation, NSError *error) { 
       NSLog(@"Error: %@", error); 
      }]; 
    //Now outside of request, so use array in some way 
    [foo received]; 
} 

Answer 1

問題不在代碼或請求中。問題是AFNetworking的GET方法是異步的，並且您試圖同步使用它。

這意味着GET方法將開始工作並坐在後臺工作，其餘代碼將繼續正常工作。只有GET請求完成後，塊內的代碼纔會運行。

此代碼爲1秒或30秒或您開始請求後的任何時間量。

放入您的行[foo received];之前的NSLog。

日誌的順序是這樣的...

1. Created NSArray called received. 
2. Pass NSArray called received to method foo. 
// some time later 
3. AFNetworking GET request finished. 
4. Assign value from the GET request to the NSArray called received. 

你需要在這種情況下，做的是把你的電話給[foo received];內完成塊。

事情是這樣的......

- (IBAction)synchronisePressed 
{ 
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager]; 

    [manager GET:@"http://foo.com/foo/" 
     parameters:nil 
      success:^(AFHTTPRequestOperation *operation, id responseObject) { 
       //Assign responseObject to received object 
       NSArray *received = responseObject; 
       NSLog(@"Woo: %@", @"got here"); 
       [foo received]; 
      } 

      failure:^(AFHTTPRequestOperation *operation, NSError *error) { 
       NSLog(@"Error: %@", error); 
      }]; 
} 

現在，您將得到...

1. Created NSArray called received. 
// some time later 
2. AFNetworking GET request finished. 
3. Assign value from the GET request to the NSArray called received. 
4. Pass NSArray called received to method foo.