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Re: Passing NSTextField Pointer to IOUSBInterfaceInterface182 Callback
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Re: Passing NSTextField Pointer to IOUSBInterfaceInterface182 Callback

  • Subject: Re: Passing NSTextField Pointer to IOUSBInterfaceInterface182 Callback
  • From: Jens Alfke <email@hidden>
  • Date: Thu, 11 Apr 2013 22:34:00 -0700
On Apr 8, 2013, at 3:07 PM, Caylan Larson <email@hidden> wrote:

> I'm doing an asynchronous read from a USB printer.  The read works correctly.  My trouble is updating a NSTextField from within the callback.

I don’t know the USB API, but I’d guess the callback gets invoked on some background thread, in which case you cannot call AppKit code from it. Your callback should instead dispatch a block to the main thread’s dispatch queue.

>                                               &(_printerOutput)

Don’t use &. It should just be _printerOutput, or perhaps (__bridge void*)_printerOutput.

—Jens
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 >Passing NSTextField Pointer to IOUSBInterfaceInterface182 Callback (From: Caylan Larson <email@hidden>)

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