在swift中设置和创建段落样式

Question

我试图移植一个客观的C方法来在PDF上下文中绘制文本到Swift.我可以转换大部分代码,但以下几行给我一个问题.转换中的一些帮助将是受欢迎的.这里是Objective C代码:

-(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)
  //.......

如果这个问题得到解决,我可以在Swift中发布完整的方法.

Answer 1

我认为这样做:

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)

我做了以下修改:

1. 我改为sizeof(alignment),UInt(sizeofValue(alignment))因为sizeof在Swift中只需要一个类型(例如sizeof(Int)).这UInt()是一个构造函数,通过此调用将Int返回的内容sizeofValue转换为UInt所需的内容.
2. 我alignmentSetting进入一个数组,以便它可以传递给UnsafePointer那种类型.这也更好地匹配原始版本.
3. 我改为CTParagraphStyleSpecifier.Alignment只是.Alignment因为第一部分不需要,因为spec是类型CTParagraphStyleSpecifier.

1在这种情况下,硬编码是正常的,因为您只传递一个值,但更通用的解决方案是:

let paragraphStyle = CTParagraphStyleCreate(alignmentSetting, UInt(alignmentSetting.count))