NSForegroundColorAttributeName在Swift中不起作用？

Question

In viewDidLoad , I have something like the following to add text attributes to a UITextField :

let textAttributes = [
    NSForegroundColorAttributeName: UIColor.whiteColor(),
    NSStrokeColorAttributeName: UIColor.blackColor(),
    NSFontAttributeName: UIFont(name: "HelveticaNeue-CondensedBlack", size: 40)!,
    NSStrokeWidthAttributeName: 1.0
]

self.textField.delegate = self
self.textField.defaultTextAttributes = textAttributes
self.textField.text = "Top text field"

All of these attributes seem to work properly, except NSForegroundColorAttributeName . This text appears transparent. Is this a Swift bug?

The text is being placed over an image in a UIScrollView . Text as it appears:

Answer 1

From Technical Q&A QA1531 :

This is because the sign of the value for NSStrokeWidthAttributeName is interpreted as a mode; it indicates whether the attributed string is to be filled, stroked, or both. Specifically, a zero value displays a fill only, while a positive value displays a stroke only. A negative value allows displaying both a fill and stroke.

So with your setting

NSStrokeWidthAttributeName: 1.0

the font is stroked only and not filled, resulting in an "outline font". You'll want to set

NSStrokeWidthAttributeName: -1.0

instead so that the font is stroked and filled.

You can find that information also if you command-click on NSStrokeWidthAttributeName in Xcode to jump to the definition:

NSNumber containing floating point value, in percent of font point size, default 0: no stroke; positive for stroke alone, negative for stroke and fill (a typical value for outlined text would be 3.0)

Answer 2

您需要使用文本属性创建NSAttributedString ，然后设置文本字段的attributedText属性：

textField.attributedText = NSAttributedString(string: "Top text field", attributes: textAttributes)