set and create paragraph style in swift - xcode

Question

I am trying to port an objective C method to draw text in a PDF context to Swift.
I could convert most of the code, but the following lines are giving me a problem.
Some help in the conversion would be welcome.
Here the Objective C code:
-(void)drawText:(NSString *)textToDraw context:(CGContextRef)myPDFContext textcolor:(NSColor *)textcolor textfont:(NSFont*)textfont textbox:(CGRect)boxsize pagesize:(CGSize)pageSize {
// .........
// create paragraph style and assign text alignment to it
CTTextAlignment alignment = kCTJustifiedTextAlignment;
CTParagraphStyleSetting _settings[] = { {kCTParagraphStyleSpecifierAlignment, sizeof(alignment), &alignment} };
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(_settings, sizeof(_settings) / sizeof(_settings[0]));
// set paragraph style attribute
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTParagraphStyleAttributeName, paragraphStyle);
// .........
}
// The following lines are my try in Swift, but this gives errors:
func DrawText(textToDraw:String, myPDFContext:CGContextRef, textcolor:NSColor, textfont:NSFont, boxsize:CGRect, pagesize:CGSize) {
var alignment = CTTextAlignment.TextAlignmentLeft
let alignmentSetting = CTParagraphStyleSetting(spec: CTParagraphStyleSpecifier.Alignment, valueSize: sizeof(alignment), value: &alignment)
let paragraphStyle = CTParagraphStyleCreate(alignmentSetting, 1)
//.......
If this is solved I could post the complete method in Swift.

Answer 1

I think this does it:
var alignment = CTTextAlignment.TextAlignmentLeft
let alignmentSetting = [CTParagraphStyleSetting(spec: .Alignment, valueSize: UInt(sizeofValue(alignment)), value: &alignment)]
let paragraphStyle = CTParagraphStyleCreate(alignmentSetting, 1)
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTParagraphStyleAttributeName, paragraphStyle)
I made the following modifications:
I changed sizeof(alignment) to UInt(sizeofValue(alignment)) because sizeof in Swift only takes a type (such as sizeof(Int)). The UInt() is a constructor that turns the Int returned by sizeofValue into the UInt needed by this call.
I make alignmentSetting into an array so that it could be passed to an UnsafePointer of that type. This also better matches the original version.
I changed CTParagraphStyleSpecifier.Alignment to just .Alignment since the first part isn't needed since spec is of type CTParagraphStyleSpecifier.
The hardcoded 1 is OK in this case because you are passing just one value, but the more general solution would be to do:
let paragraphStyle = CTParagraphStyleCreate(alignmentSetting, UInt(alignmentSetting.count))

Answer 2

Here the full working method based on the corrections and help.
func drawText(textToDraw:String, myPDFContext:CGContextRef, textcolor:NSColor, textfont:NSFont, boxsize:CGRect, pagesize:CGSize) {
let _font = NSFont(name:textfont.fontName, size:textfont.pointSize )
if (_font == nil) {
println("Font [\(textfont)] does not exist")
return
}
let myBoxWidth = boxsize.size.width
let myBoxHeight = boxsize.size.height
let myBoxxpos = boxsize.origin.x
let myBoxypos = boxsize.origin.y
let frameRect = CGRectMake(myBoxxpos, myBoxypos,myBoxWidth,myBoxHeight);
let framePath = CGPathCreateMutable()
CGPathAddRect(framePath, nil, frameRect);
// create attributed string
let attrStr = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
CFAttributedStringReplaceString (attrStr, CFRangeMake(0, 0), textToDraw);
// create font
let font = CTFontCreateWithName(textfont.fontName, textfont.pointSize, nil);
var alignment = CTTextAlignment.TextAlignmentLeft
let alignmentSetting = [CTParagraphStyleSetting(spec: .Alignment, valueSize: UInt(sizeofValue(alignment)), value: &alignment)]
//let paragraphStyle = CTParagraphStyleCreate(alignmentSetting, 1)
let paragraphStyle = CTParagraphStyleCreate(alignmentSetting, UInt(alignmentSetting.count))
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTParagraphStyleAttributeName, paragraphStyle)
// set font attribute
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTFontAttributeName, font);
// set color attribute
CFAttributedStringSetAttribute(attrStr,CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTForegroundColorAttributeName,textcolor.CGColor);
// Prepare the text using a Core Text Framesetter.
let framesetter = CTFramesetterCreateWithAttributedString(attrStr);
// Get the frame that will do the rendering.
let currentRange = CFRangeMake(0, 0);
let frameRef = CTFramesetterCreateFrame(framesetter, currentRange, framePath, nil);
// Put the text matrix into a known state. This ensures
// that no old scaling factors are left in place.
CGContextSetTextMatrix(myPDFContext, CGAffineTransformIdentity);
// Draw the frame.
CTFrameDraw(frameRef, myPDFContext);
}