CODEWITHSUNDEEP
iosmultithreading
a_tuo
a_tuo

Reputation: 659

enumerateObjects block main UI?

I try to fetch all GIF in Photos in async block like this:

DispatchQueue.main.async {
  allImageFetchResult.enumerateObjects(options: .concurrent, using: {(asset, _, _) in
    if asset.isGIF {
      assetSet.insert(asset)
    }
  })
}

But, it seems block user interface, the interface doesn't response to my touch actions until the block task is complete.

Upvotes: 0

Views: 335

Answers (4)

Dharma
Dharma

Reputation: 3013

Make completion handler to get data once fetching is done.Like below check it out..

      dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {  
          self.fetchAllPhotos{ data in 
            print(data)
            dispatch_async(dispatch_get_main_queue()) {
              // update the user interface..
             print("updating UI")
            }
         }
      }

    func fetchAllPhotos(completion: (data:PHAsset) -> ())
    {
     allImageFetchResult.enumerateObjects(options: .concurrent, using: {(asset, _, _) in
        if asset.isGIF {
          assetSet.insert(asset)
        }
      })
      completion(assetSet)
    }

Upvotes: 0

Mihir Thanekar
Mihir Thanekar

Reputation: 518

DispatchQueue.main.async allows the UI updates to be on the main thread asynchronously. When you enumerate the objects, you are doing a synchronous task. See https://developer.apple.com/documentation/photos/phfetchresult/1620998-enumerateobjects

Discussion: This method executes synchronously.

So what you should do is enumerate beforehand, and only update the UI in the DispatchQueue.

Upvotes: 1

Aravind A R
Aravind A R

Reputation: 2714

Here you are fetching GIFs from the main thread and that's the reason why your UI is not responding to touches. Instead of main queue use DispatchQueue.global fetch GIFs from background thread. Try using 

DispatchQueue.global().async {
 allImageFetchResult.enumerateObjects(options: .concurrent, using: {(asset, _, _) in
    if asset.isGIF {
      assetSet.insert(asset)
    }
  })
}

Upvotes: 1

Malik
Malik

Reputation: 3802

The UI is non-responsive because you are fetching your data on the UI thread (main queue). If you want your UI to continue to be responsive, you need to move the fetch code onto another thread (probably background queue)

Upvotes: 0

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