样式占位符文本 NSSearchField 和 NSTextField？

Question

我一直在创建一个 MacOS 应用程序，但在设置 NSSearchField（名为 searchField）的字体样式时遇到了问题。到目前为止我的代码如下：

在单个主函数的顶部声明 viewController class:

let normalTextStyle = NSFont(name: "PT Mono", size: 14.0)

let backgroundColour = NSColor(calibratedHue: 0.6,
                               saturation: 0.5,
                               brightness: 0.2,
                               alpha: 1.0)

let normalTextColour = NSColor(calibratedHue: 0.5,
                               saturation: 0.1,
                               brightness: 0.9,
                               alpha: 1.0)

在 viewDidLoad 中声明：

searchField.backgroundColor = backgroundColour
searchField.textColor = normalTextColour
searchField.font = normalTextStyle
searchField.centersPlaceholder = false
searchField.currentEditor()?.font = normalTextStyle
let attrStr = NSMutableAttributedString(string: "Search...",
                                        attributes: [NSForegroundColorAttributeName: normalTextColour])
searchField.placeholderAttributedString = attrStr

通常这会起作用，但在一种情况下除外：当搜索字段具有焦点但未输入搜索词时。在这种情况下，占位符文本具有正确的颜色，但字体似乎 return 为默认值（Helvetica 12 磅？）。一旦输入内容或字段失去焦点，就会再次使用正确的字体。

我曾尝试通过 Apple 文档查找当前未设置的某种字体或颜色设置，但没有成功。我摆弄了所有可以在界面生成器中找到的字体设置，包括 cocoa 绑定和检查器中的常规设置。

我需要给currentEditor设置一些值吗？我猜不是因为输入文本后字体会更改。我被卡住了 - 谁能帮忙？

编辑：我现在尝试使用 NSTextField，结果是一样的。有人有什么想法吗？

Answer 1

我最终找到了答案。我创建了一个 Formatter 类型的新 class TitleTextFormatter，即“is intended for subclassing. A custom formatter can restrict the input and enhance the display of data in novel ways”。我需要做的就是覆盖某些默认函数以获得我需要的东西：

import Cocoa

class TitleTextFormatter: Formatter {

  override func string(for obj: Any?) -> String? {    
    /*
     * this function receives the object it is attached to.
     * in my case it only ever receives an NSConcreteAttributedString
     * and returns a plain string to be formatted by other functions
     */

    var result: String? = nil
    if let attrStr = obj as? NSAttributedString {
        result = attrStr.string
    }
    return result
  }

  override func getObjectValue( _ obj: AutoreleasingUnsafeMutablePointer<AnyObject?>?,
                                for string: String,
                                errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
    /* 
     * this function in general is overridden to provide an object created 
     * from the input string. in this instance, all I want is an attributed string
     */

    let titleParagraphStyle = NSMutableParagraphStyle()
    titleParagraphStyle.alignment = .center

    let titleAttributes = [NSAttributedStringKey.foregroundColor: NSColor.mainText,
                           NSAttributedStringKey.font: NSFont.titleText,
                           NSAttributedStringKey.paragraphStyle: titleParagraphStyle]

    let titleAttrStr = NSMutableAttributedString(string: string,
                                                 attributes: titleAttributes)

    obj?.pointee = titleAttrStr
    return true
  }

  override func attributedString(for obj: Any,
                               withDefaultAttributes attrs: [NSAttributedStringKey : Any]? = nil) -> NSAttributedString? {
    /* 
     * is overridden to show that an attributed string is created from the
     * formatted object. this happens to duplicate what the previous function 
     * does, only because the object I want to create from string is an 
     * attributed string
     */

    var titleAttrStr: NSMutableAttributedString?

    if let str = string(for: obj) {
        let titleParagraphStyle = NSMutableParagraphStyle()
        titleParagraphStyle.alignment = .center

        let titleAttributes = [NSAttributedStringKey.foregroundColor: NSColor.mainText,
                               NSAttributedStringKey.font: NSFont.titleText,
                               NSAttributedStringKey.paragraphStyle: titleParagraphStyle]

        titleAttrStr = NSMutableAttributedString(string: str,
                                                 attributes: titleAttributes)
    }

    return titleAttrStr

  }

}

然后在 viewDidLoad 中添加了以下内容：

let titleTextFormatter = TitleTextFormatter()
titleTextField.formatter = titleTextFormatter

样式占位符文本 NSSearchField 和 NSTextField？

Style placeholder text NSSearchField and NSTextField?

macos

fonts

nssearchfield

swift