On Sep 2, 2010, at 3:17 PM, David Duncan wrote: > On Sep 2, 2010, at 11:29 AM, vincent habchi wrote: > >> You mean I shall use your dispatch_async invocation instead of calling >> [layer setNeedsDisplay]? > > Calling -setNeedsDisplay arranges for -display to later be called on the > current runloop. As such using -setNeedsDisplay is reliant on a runloop > running (and running regularly) neither of which you have on a GCD queue. > >> I was thinking of calling dispatch_async () inside -drawInContext, but, if I >> understand your example correctly, this is wrong. > > Doing so would cause you all manners of pain and suffering, the most common > of which is things "mostly" working but occasionally your drawing going into > the wrong view. Basically *never* use the context given to you in > -drawInContext: outside of that invocation.
More generally, -draw…: methods should never have side effects, whether we're talking about a layer, a view, or what have you. -jcr _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
