Objective-C

Question

在每个循环中，我使用用于执行 JSON 调用的 ID 初始化连接器 class。问题是，此循环在连接器 class 的 connectionDidFinishLoading 委托方法完成之前继续迭代，根据需要解析 JSON，然后使用委托方法及其检索到的信息。

for(NSDictionary *item in views){

   NSInteger myID = [[item valueForKey:@"id"] integerValue];

 //filter contains these two dictionaries
   NSDictionary *ownerDictionary = [filterDictionary valueForKey:@"owner"];
   NSString *ownerDisplayName = [ownerDictionary valueForKey:@"displayName"];

   self.projectName = projectName;
   self.ownerName = ownerDisplayName;


   //value inside dictionary for owner
   NSString *ownerDisplayName = [ownerDictionary valueForKey:@"displayName"];

   //I initialize the connector class here
   self.sprintConnector = [[SprintConnector alloc] initWithId:myID];
   [self.sprintConnector setDelegate:self];



//**I do not want to continue this loop until the delegate method that i implement is called**/
}

//implementation of delegate method 
-(void)didFinishLoadingStuff:(MyObject *)obj{

    Project *newProject = [[Project alloc] init];
    newProject.projectName = self.projectName;
    newProject.projectOwner = self.ownerName;
    newProject.sprint = sprint;
   //Ok now i have the information that i need, lets continue our loop above
}

//连接器class设置请求的方法在这里：

-(void)retrieveSprintInfoWithId{

    NSURLConnection *conn;
    NSString *urlString = @"myJSONURL";
    NSURL *url = [NSURL URLWithString:[urlString stringByAppendingString:self.ID]];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
//    conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    conn = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    NSLog(@"data coming from request: %@", data );
    [self.data appendData:data];

}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection{

    NSLog(@"we finished loading");
    NSError *error = nil;

    self.projectsDict = [[NSDictionary alloc] initWithDictionary:[NSJSONSerialization JSONObjectWithData:self.data options:NSJSONReadingMutableContainers error:&error]];

    NSLog(@"Our sprint array with id: %@ %@", self.ID, self.projectsDict);

//this is where we parse the JSON then use the delegate method that the above class will implement
    [self parseJSON];

}



-(void)parseJSON{

[self.delegate didFinishLoadingStuff:SomeObject];
}

我希望能够强制调用 connectionDidFinishLoading 方法 ->parseJSON->delegate 方法，并在循环继续之前完成上述方法的实现。

我有哪些选择？最佳实践？ ETC？

Answer 1

你想做的是同步发出请求，我会告诉你怎么做，但你不应该那样做，所以在我告诉你如何发出同步请求之后，我会告诉你如何做应该处理这个

1- 要同步发出请求，您可以使用 NSURLConnection 的 sendSynchronousRequest 方法，这将阻塞直到接收到数据和 return 数据，这里是 docs。你不应该这样做，因为你可能会阻塞主线程，这会导致糟糕的用户体验（还有其他原因导致这是不好的做法）

2- 你应该像在示例代码中那样发出异步请求，在你的回调中你应该获取适当的对象（你应该通过项目 ID 知道），然后做你需要的任何事情对该对象执行操作...如果您需要加载所有内容以便执行某些操作，那么您应该跟踪它（发送的请求与收到的响应）

希望对您有所帮助

丹尼尔

Objective-C - 阻止循环继续直到调用委托方法

Objective-C - block loop from continuing until delegate method is called

json

objective-c-blocks

grand-central-dispatch

nsurlconnectiondelegate