Is there a better way of coercing CFArray to a swift array?

CTFrame.swift

import CoreText

extension CTFrame {

	var lines: [CTLine] {

		// This is the only way I've currently found to get the 
		// CFArray of CTLines to cast to a swift array.
		let linesAO: [AnyObject] = CTFrameGetLines(self) as [AnyObject]
		guard let lines = linesAO as? [CTLine] else {
			return []
		}

		return lines
	}
}

CTPlayground.swift

// This is the code I have that uses the code above.
// It doesn't work in a playground though for some reason.

import CoreText

extension CTFrame {

	var lines: [CTLine] {

		// This is the only way I've currently found to get the
		// CFArray of CTLines to cast to a swift array.
		let linesAO: [AnyObject] = CTFrameGetLines(self) as [AnyObject]
		guard let lines = linesAO as? [CTLine] else {
			return []
		}

		return lines
	}
}

let attributes: [String : AnyObject] = [
	String(kCTFontAttributeName): CTFontCreateWithName("HelveticaNeue", 40, nil)
]

let text = "Hello World"
let rect = CGRect(origin: CGPoint(), size: CGSize(width: 120, height: 500))
let string = CFAttributedStringCreate(nil, text, nil)
let framesetter = CTFramesetterCreateWithAttributedString(string)
let framePath = CGPathCreateWithRect(rect, nil)
let frame = CTFramesetterCreateFrame(framesetter, CFRange(), framePath, nil)

let lines = frame.lines

Hello Bryan,

I began using Swift one week ago and doesn't understand how to use.
I think I can get the list of network interfaces of my Mac using "let netInterfaces = SCNetworkInterfaceCopyAll()" but this give a CFArray.
I can't use this CFArray in a for loop as "for netInterface in netInterfaces".

Can you explain how to use your advise ?

Thanks
Bertrand