offloading

Let's be plain about it: UIKit (which basically cover all of the UI Thread territory) isn't thread safe and the things that draw the view hierarchy run on the main thread. The rare exceptions are outstanding enough that they get mentioned explicitly in the documentation as being thread safe or being designed to run in another thread/queue.On the other hand, it really depends on what you're doing and what sorts of latency you're allowing for how much you can offload to another thread. Because the straight forward way of offloading things that were originally done on the main thread to a background thread ends up looking a lot like this: You've got an action method that's responding to the user tapping a button. Gather up all of the relevant parameters and dispatch a block to the worker queue.Inside that worker block, do the computation and work. Gather up the relevant results and dispatch a block to the main queue. Inside this second block, use the passed in results to update the user interfa

If there is a way to achieve, then How can I upload/download data after 30 minutes of app went backgrond?.Two things:iOS provides no general mechanism for an app to schedule itself to be resumed at a specific time.If an app is running, it has full access to the network, regardless of whether it’s in the foreground or background. The only gotcha is that devices with WWAN will typically shut down Wi-Fi when the device is locked.I’m confused about your upload requirement. If you’re suspended in the background there should be no need to upload data because you can’t possibly have generated new data that warrants uploading.As far as downloads are concerned, my standard recommendation in this space is to have your app offload the decision about what data needs to be dowloaded to a server. When the server decides that the app needs some data it can send it a silent push notification to the app, in response to which the app can kick off the download.IMPORTANT You can use silent push notifications as a mechan

Honestly that sounds like a bug in the driver; it seems obvious that the driver’s checksum offload should behave the same as kernel’s.I don’t know if there’s a way around this; if you want a definitive answer, you should open a DTS tech support incident and I, or one of my colleagues, can dig into it.Share and Enjoy — Quinn “The Eskimo!” Apple Developer Relations, Developer Technical Support, Core OS/Hardware let myEmail = eskimo + 1 + @apple.com

Thanks for the prompt reply.The problem however, seems to be that the checksum verification is offloaded to the NIC. There are kernel parameters (ending in hwcksum_rx for example) that indicate this. This means that the NIC does not even deliver the UDP packets with a zero checksum to the system and the function udp_input_checksum is not even called.It also seems that the involved kernel parameters cannot be altered. (not even when the System Integrity Protection is switched off, which would not have been a viable solution anyway).So the question remains, how to get the UDP packets with their checksum set to zero?

My app lets you know if there are upcoming events in your area and it would be nice if it could check every week or so with my server to see if there were any and update the users local Notifications. So this would require it to run in the background and access the web.iOS has a mechanism for this, namely background fetch. You learn more about it in the Background Execution section of the App Programming Guide for iOS.However, if your app is not being run regularly by the user then it’s likely that your app will fall off the background fetch radar. The best way to meet your requirements is to offload this periodic work to a server. That is, have your server poll the event database and, if there’s anything relevant for this user, post a push notification. That is power efficient (no code needs to execute on the user’s device) and reliable.Share and Enjoy — Quinn “The Eskimo!” Apple Developer Relations, Developer Technical Support, Core OS/Hardware let myEmail = eskimo + 1 + @apple.com

Xcode is not itself a compiler, it just hosts the compiler. For Obj-C, the current (preferred) compiler is clang. You can visit clang.llvm.org and if your question isn't answered by the information on the site, there are mailing lists where you can ask about implementation details and strategy.My guess, though, is that the compiler isn't designed to use the GPU.>> No reason for it to need the GPU when buildingNo particular reason, but it's certainly possible that it might use something like OpenCL to offload some processing onto the GPU.

No, atomicity doesn't change anything. The value of the property is a pointer (to a mutable array), so atomicity would protect only the accessing of the pointer, not the data structures pointed to.It's a complete waste of time looking for a generic solution, such as encasing random blocks of code in a synchronizing construct. You'll either leave hard-to-find bugs in the edge cases, or hard-to-find deadlocks.In this case, we can't even speculate on a real solution, because we don't know what's going on. We don't even know if scanQueue is serial or concurrent. We don't know what the point of using NSOperation is: is it to get parallel processing, to offload long tasks from the main thread, etc? Maybe NSOperation isn't the best API to use for this, perhaps direct use of GCD is easier. The code you showed has each NSOperation using, or not using, the resulting array of the previous operation, according to the timing of the block placed back on the main thread. We don't know the consequences of this sort