CODEWITHSUNDEEP
objective-ccocoaswift
Morten J
Morten J

Reputation: 914

Is this system object pointer code at all possible in Swift?

I was pointed to this objc snippet from WWDC 14, but I work on a Swift project. 

CMIOObjectPropertyAddress   prop    = {
    kCMIOHardwarePropertyAllowScreenCaptureDevices,
    kCMIOObjectPropertyScopeGlobal,
    kCMIOObjectPropertyElementMaster
};
UInt32                      allow   = 1;

CMIOObjectSetPropertyData(kCMIOObjectSystemObject, &prop, 0, NULL, sizeof(allow), &allow);

I then tried rewriting to Swift:

var prop : CMIOObjectPropertyAddress {
    kCMIOHardwarePropertyAllowScreenCaptureDevices
    kCMIOObjectPropertyScopeGlobal
    kCMIOObjectPropertyElementMaster
}

var allow:UInt32 = 1
CMIOObjectSetPropertyData(kCMIOObjectSystemObject, &prop, 0, nil, sizeof(UInt32), &allow)

But it doesn't even validate. I don't know how to translate the CMIOObjectPropertyAddress struct. Xcode says

/Users/mortenjust/Dropbox/hack/learning/screenrec/screenrec/deleteme.swift:32:61: Cannot assign to a get-only property 'prop'

Upvotes: 1

Views: 489

Answers (2)

Morten J
Morten J

Reputation: 914

You're right, just got it running right this second. Turns out I also had to correct for some of the types. Here's the complete translation: 

        var prop = CMIOObjectPropertyAddress(
        mSelector: CMIOObjectPropertySelector(kCMIOHardwarePropertyAllowScreenCaptureDevices),
        mScope: CMIOObjectPropertyScope(kCMIOObjectPropertyScopeGlobal),
        mElement: CMIOObjectPropertyElement(kCMIOObjectPropertyElementMaster))

    var allow : UInt32 = 1
    var dataSize : UInt32 = 4
    var zero : UInt32 = 0
    CMIOObjectSetPropertyData(CMIOObjectID(kCMIOObjectSystemObject), &prop, zero, nil, dataSize, &allow)

    var session = AVCaptureSession()
    session.sessionPreset = AVCaptureSessionPresetHigh

    var devices = AVCaptureDevice.devices()
    for device in AVCaptureDevice.devices() {
        println(device)
    }

Upvotes: 3

matt
matt

Reputation: 535306

A C struct translates as a Swift struct. Use the implicit memberwise initializer:

    var prop = CMIOObjectPropertyAddress(
        mSelector: UInt32(kCMIOHardwarePropertyAllowScreenCaptureDevices),
        mScope: UInt32(kCMIOObjectPropertyScopeGlobal),
        mElement: UInt32(kCMIOObjectPropertyElementMaster))

The cool part is when you type CMIOObjectPropertyAddress(, code completion gives you the rest.

Upvotes: 3

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