One NSOperationQueue per cell or per UIViewController?

Question

I have a UITableView where I download data from a remote server one by one when the cells appear.

Is it safe to create one NSOperationQueue per cell? I am worried that this may trigger thread explosion (if there are too many threads). Having NSOperationQueue per cell instance is easier for development, because once the cell gets reused, I can just cancel all operations on the NSOperationQueue.

In contrast, if I use one NSOperationQueue per UIViewController, then I can pass the NSOperationQueue to the cell, and the cell can add its NSOperation to that queue. But, I need to handle in some way such that I can cancel that operation when the cell gets reused (store reference to the NSOperation in a dictionary inside the UIViewController, etc.).

Most tutorials have one NSOperationQueue in the UIViewController, but I have seen one where he used one NSOperationQueue for each cell.

the best example developer.apple.com/library/ios/samplecode/LazyTableImages/… by Apple just follow it . — Prashant Tukadiya
hey @MikeAlter do you have other reasons, not just because the Apple sample code uses this approach, or other tutorials also use that approach? thanks — Dj S
i have implemented that example ,the way of ws calling and image downloading is awesome and also performance friendly — Prashant Tukadiya

Hitesh Surani Hitesh Surani · Accepted Answer · 2016-07-14T08:08:20

In given below tutorial provide the option for the cancel operation and also resume operation according to your requirement.

A good example from Ray Wenderlich : http://www.raywenderlich.com/19788

Update:

If you have use NSOperationQueue in UITableView then You need to manage properly. For example AFNetworking library have use NSOperationQueue for image downloading from url and other task that's work fine. So my suggestion is if you want use NSOperationQueue in UITableView then manage it properly otherwise it definitely cause an issue in future to handle long data.

One NSOperationQueue per cell or per UIViewController?

1 Answers