Objective-c - Issues about pausing and resuming NSURLSessionDownloadTask

Question

I packaged a network download tool today and found a problem. When I pause a task, after waiting for a period of time, a timeout error will appear in the proxy method. I don’t know what happened; (click [task suspend] ] a task, the network requests of this task are not all suspended, and then click [task resume] the task is not all resumed (no caching), but in my case, when I click [task resume] suspend] a task, and then after waiting for a period of time, the agent method will have a timeout situation. Clicking [task resume] has no effect. How can a timeout error occur here? Thank you for your help)