Just do the calculation within a dispatch_async within computeSimething.
On Mar 14, 2016, at 4:17 AM, Gerriet M. Denkmann wrote: > >> On 14 Mar 2016, at 14:17, Quincey Morris >> <[email protected]> wrote: >> >> On Mar 13, 2016, at 23:50 , Gerriet M. Denkmann <[email protected]> wrote: >>> >>> - (void)computeSomething >>> { >>> self.message1 = @“Start computing”; >>> // some seconds of computations >>> self.message1 = @“Result = 42”; >>> } >> >> Assume, conceptually, that drawing only takes place asynchronously (that is >> to say, setting a new value on the string invokes setNeedsDisplay, that’s >> all), and it’s obvious why this isn’t going to work. >> >> But the real issue is not that the text field won’t update, it’s that you’re >> blocking the main thread with computation. You should move the computation >> off the main thread — using dispatch_async to a default queue. At the end of >> the computation, go back to the main thread (dispatch_async again, >> specifying the main queue this time) and put the result in the text field. >> >> This is, of course, going to introduce threading issues into your design. If >> the background thread keeps its results private (within the thread) until >> you switch back to the main thread, you can actually update any permanent >> data structures on the main thread, avoiding the need for locks or other >> synchronization techniques. However, you have to arrange for the main thread >> to avoid trying to use the results before the background computation is >> done, or to start any new computations, until the old ones are done, as far >> as such safety checks are necessary for your app. >> >> (You can use NSOperationQueue instead of GCD, but I don’t see a lot of >> advantage in that. The consequences are the same.) > > You are absolutely right that a background would be the right thing. > But this is just a small tool for testing, and it will not take more than a > few seconds, so I am trying to avoid this. > > But I have found a solution (you mentioning setNeedsDisplay was a great help): > > - (void)computeSomething > { > self.textField1.stringValue = @“Start computing”; > [self.textField1 display]; > // some seconds of computations > self.textField1.stringValue = @“Result = 42”; > } > > Gerriet. > > > > _______________________________________________ > > Cocoa-dev mailing list ([email protected]) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/zav%40mac.com > > This email sent to [email protected] _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
