如何在GET请求之外使用变量？

Question

我想：

• 一个GET请求（AFNetworking）
• 分配给请求成功
• 使用变量一旦请求完成内部变量初始化变量之前

---

我得到的错误：

• 当试图GET请求之后做一些变量，它打破了，自称有给变量没有值尚未

---

以下是我的代码，我该如何解决这个问题问题？

- (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

问题不在代码或请求中。问题是AFNetworking的GET方法是异步的，并且您试图同步使用它。

这意味着GET方法将开始工作并坐在后台工作，其余代码将继续正常工作。只有GET请求完成后，块内的代码才会运行。

此代码为1秒或30秒或您开始请求后的任何时间量。

放入您的行[foo received];之前的NSLog。

日志的顺序是这样的...

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. 

你需要在这种情况下，做的是把你的电话给[foo received];内完成块。

事情是这样的......

- (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); 
      }]; 
} 

现在，您将得到...

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.