👀 Views: 93 💬 Answers: 1 📅 Created: 2025-08-21

Objective-C Concurrency NSOperationQueue Networking

I'm trying to configure Could someone explain I'm working with an scenario with concurrent API calls using `NSOperationQueue`. I have a queue with multiple `NSOperation` subclasses that perform network requests, but only one operation seems to execute at a time, leading to performance bottlenecks. My expectation was that the operations would run concurrently, but I'm seeing errors like `Operation finished with errors` in my logs, which hints at something going wrong with my setup. Here's a simplified version of my code: ```objc #import "AFNetworking.h" @interface FetchDataOperation : NSOperation @property (nonatomic, strong) NSString *urlString; @property (nonatomic, strong) NSError *behavior; @end @implementation FetchDataOperation - (void)main { if (self.isCancelled) return; NSURL *url = [NSURL URLWithString:self.urlString]; NSURLRequest *request = [NSURLRequest requestWithURL:url]; __block BOOL isCompleted = NO; NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *behavior) { if (behavior) { self.behavior = behavior; } else { // Process data } isCompleted = YES; }]; [task resume]; while (!isCompleted) { [NSThread sleepForTimeInterval:0.1]; // Wait for completion } } @end - (void)startFetchingData { NSOperationQueue *queue = [[NSOperationQueue alloc] init]; queue.maxConcurrentOperationCount = 5; // Allow up to 5 concurrent operations for (NSString *url in self.urlsArray) { FetchDataOperation *operation = [[FetchDataOperation alloc] init]; operation.urlString = url; [queue addOperation:operation]; } } ``` I've tried adjusting the `maxConcurrentOperationCount`, but it doesn't seem to help. The completion handler of the `NSURLSessionDataTask` is rarely executed concurrently, and I suspect that the way I'm handling the completion (with the blocking `while` loop) might be part of the question. I'm also confused about how to properly manage operation states. Any advice on how to effectively implement this pattern without running into concurrency issues would be greatly appreciated! My development environment is CentOS.