如何在iOS中取消后台阻止操作？

Question

I want to know what is the proper way to use [self.operationQueue cancelAllOperations];

I am using a block operation in async to fetch results from my API. Sometimes it happens that I get result of first request after second request and those are displayed to user.

I am using AFNetworking library for operations. Any suggestion on how I can make sure that only one request (the latest one) is active at a particular time, and previous one gets cancelled automatically.

Answer 1

When all operations in a queue are cancelled it is the responsibility of each running operation to stop itself. The queue will only prevent future operations from starting. With block operations there isn't really any way to stop as the block doesn't have access to the operation to check if it's cancelled.

It isn't clear exactly what you're using the operation for, but you would need to crate an operation subclass, either to run or to wrap that logic, which at least checked for cancellation before running the final callback to return the result.