Re: [Pyobjc-dev] Problem with NSText:setString

[Ronald O. <ron...@ma...>]

On 13 Jun, 2011, at 14:07, Daniel Luis dos Santos wrote:

> Hello,
> 
> I have a GUI application built with interface builder. One of the windows has a NSTextView in it. I connected it to an object also referenced in the interface builder file.
> The goal is to write to the NSTextView from a background trhead that does some task. I launch the thread with a call to 
> 
> 	NSThread.alloc().initWithTarget_selector_object_()
> 
> The behaviour I am getting is erratic. Most times it blocks on the call to the NSTextView's setString_() method and the application hangs. If I run the code on the main thread it runs fine.
> 
> How do I do this from a background thread ? The idea is to keep the application responsive.

You cannot call methods of GUI classes from a thread that is not the main thread (that is, AppKit is not thread-safe).  You need to look into methods like, "-performSelectorOnMainThread:withObject:waitUntilDone:".

The basic pattern is that you launch your long running task in a secondary thread and use performSelectorOnMainThread... to call a method that updates the GUI.  This should keep the application responsive as the GUI updating code should be simple and not take a lot of time.

Ronald

> 
> I am on :
> snow leopard (10.6.7)
> pyObjc (I think it is 2.2b3 (can you tell me how to really check the version ?))
> 
> Many thanks
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