Can anyone provide an example (preferably in C++) of how to read the EDID data for the current display?
I can do it on an Intel based Mac, the same code does not work on the new Apple M1 devices. The Intel code looks something like:
CFMutableDictionaryRef matching = IOServiceMatching("IODisplayConnect");
io_iterator_t iter = 99;
kern_return_t err = IOServiceGetMatchingServices( kIOMasterPortDefault, matching, &iter );
io_service_t serv;
serv = IOIteratorNext( iter );
CFDictionaryRef displayInfo;
displayInfo = IODisplayCreateInfoDictionary( serv, kIODisplayOnlyPreferredName );
( . . . )
It appears that the new Apple M1 devices have a new video architecture, so the IOServiceMatching / IOServiceGetMatchingServices on longer works.
alanfromtewksbury
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The following code sequence works on Catalina and on Intel Big Sur devices, it does not work on the new Apple M1 devices running Big Sur.
CFMutableDictionaryRef matching = IOServiceMatching("IODisplayConnect");
io_iterator_t iter = 99;
kern_return_t err = IOServiceGetMatchingServices( kIOMasterPortDefault, matching, &iter );
The "matching" variable seems valid:
matching CFMutableDictionaryRef 1 key/value pair
[0] "IOProviderClass" : "IODisplayConnect"
		key __NSCFConstantString * "IOProviderClass"
		value __NSCFString * "IODisplayConnect"
The call to "IOServiceGetMatchingServices" sets the "iter" value to 0.
If I use another class name in the "IOServiceMatching" call, say "IOMediaBSDClient", "IOServiceGetMatchingServices" returns a valid iterator.
Would Big Sur on Apple M1 devices need additional calls, or has this service class been deprecated?
Using "IODisplayConnect" allows me to get display information via "IODisplayCreateInfoDictionary".
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