Swift 2.0：在没有更多上下文的情况下，表达类型不明确-字典

Question

I have the following code that used to work fine in Swift 1.2. Now, I've upgrade to Swift 2.0 and it no longer works with the following message:

attributes:Dictionary - Type of expression is ambiguous without more context

 var _text: NSString = self.text as NSString!
 var paragraphStyle : NSMutableParagraphStyle = NSMutableParagraphStyle()
 paragraphStyle.lineBreakMode =  lineBreakMode
 var attributes:Dictionary = [NSFontAttributeName:self.font, NSParagraphStyleAttributeName:paragraphStyle]
 var prefixTextSize: CGSize = _text.sizeWithAttributes(attributes)

Im unsure how to fix this as it used to work fine. Any suggestions?

Answer 1

You could try specifying the type for the dictionary more clearly, if that's not the problem it might point the way (as @Martin suggests could be an optional requiring unwrapping).

For example:

var attributes: [String:NSObject] 
    = [NSFontAttributeName:self.font, NSParagraphStyleAttributeName:paragraphStyle]

Answer 2

@Martin R was correct. I fixed it by unwrapping self.font

var attributes:Dictionary = [NSFontAttributeName:self.font!, NSParagraphStyleAttributeName:paragraphStyle]