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macosswiftcocoabrightness

Adjust screen brightness in Mac OS X app

I want to control the brightness of the main-screen within my Mac OS X app (like the F1/F2 buttons). In iOS, there's something like this:

UIScreen.mainScreen().brightness = CGFloat(0.5)

In OSX we have NSScreen, which is nice to find out what the main-screen is, but it misses the .brightness method.

So how can I adjust the monitor brightness using Swift on OSX?

Solution

  • There's no such nice API for doing this on OS X.

    We have to use IOServiceGetMatchingServices to find "IODisplayConnect" (the display device) then use the kIODisplayBrightnessKey to set the brightness:

    func setBrightnessLevel(level: Float) {
    
    var iterator: io_iterator_t = 0
    
    if IOServiceGetMatchingServices(kIOMainPortDefault, IOServiceMatching("IODisplayConnect"), &iterator) == kIOReturnSuccess {
        
        var service: io_object_t = 1
        
        while service != 0 {
            
            service = IOIteratorNext(iterator)
            IODisplaySetFloatParameter(service, 0, kIODisplayBrightnessKey as CFString, level)
            IOObjectRelease(service)
            
        }
        
    }
}

setBrightnessLevel(0.5)