如何使用 TextKit（不是 NSAttributedStrings）在 UITextView 中获取属性信息

Question

我有一个 UITextView 和带有 UITextKit 样式 (NSStrikethroughStyleAttributeName) 的 TextKit：

这是我的代码：

@IBOutlet weak var textView: UITextView!
var dict = [String: AnyObject]()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let newFont = UIFont(name:"HelveticaNeue", size: textView.font!.pointSize)
    self.textView.font = newFont
    dict[NSFontAttributeName] = newFont
    
    let selectedRange: NSRange  = NSMakeRange(12,6)
    self.makeStrikeThrough(selectedRange)
    
}

func makeStrikeThrough(selectedRange: NSRange) {
    dict[NSStrikethroughStyleAttributeName] = 2
    self.textView.textStorage.beginEditing()
    self.textView.textStorage.setAttributes(dict, range: selectedRange)
    self.textView.textStorage.endEditing()
}

现在我必须有办法检测这个字体属性。有什么方法可以获取信息：

在 selectedRange: NSRange 12, 6 我使用属性 NSStrikethroughStyleAttributeName 和属性 2，也许作为数组项???

欢迎任何想法！

Answer 1

唯一属性范围的离散化（w.r.t。left/right 这些的相邻范围）

您可以重复使用 NSAttributedString 的 attributesAtIndex(location:effectiveRange:) 方法，将整个属性字符串的范围编码为子范围列表，每个子范围包含一组属性和这些值。

Declaration:
func attributesAtIndex(location: Int, 
     effectiveRange range: NSRangePointer) -> [String : AnyObject]
Description:

Returns the attributes for the character at a given index.

Return value:

The attributes for the character at index.

更具体地说，使用 attributesAtIndex(...) 创建 NSAttributedString 的扩展 return 和元组数组，元组定义为

第一个元组元素是一组不同属性（或缺少）的范围。
第二个元组元素本身就是一个元组数组，这些元组定义为：
- 第一个子元组元素是属性名称。
- 第二个子元组元素是属性值。
或者，第二个元组元素是一个 [String: AnyObject] 数组，对应于属性及其各自的值（两种变体都包含在下面）

属性字符串中由多个属性赋予的范围自然会 return 几个元素的内部元组数组，而根本没有属性的范围将 return 一个空的内部元组数组.

分机（二选一）如下：

/* let 2nd tuple be an array of tuples itself */
extension NSAttributedString {
    func getAttributes() -> [(NSRange, [(String, AnyObject)])] {
        var attributesOverRanges : [(NSRange, [(String, AnyObject)])] = []
        var rng = NSRange()
        var idx = 0

        while idx < self.length {
            let foo = self.attributesAtIndex(idx, effectiveRange: &rng)
            var attributes : [(String, AnyObject)] = []

            for (k, v) in foo { attributes.append(k, v) }
            attributesOverRanges.append((rng, attributes))

            idx = max(idx + 1, rng.toRange()?.endIndex ?? 0)
        }
        return attributesOverRanges
    }
}

/* or, let 2nd tuple be a [String: AnyObject] dictionary */
extension NSAttributedString {
    func getAttributes() -> [(NSRange, [String: AnyObject])] {
        var attributesOverRanges : [(NSRange, [String: AnyObject])] = []
        var rng = NSRange()
        var idx = 0

        while idx < self.length {
            let foo = self.attributesAtIndex(idx, effectiveRange: &rng)
            attributesOverRanges.append((rng, foo))

            idx = max(idx + 1, rng.toRange()?.endIndex ?? 0)
        }
        return attributesOverRanges
    }
}

用法示例：

/* Example setup */
let fooString = "foo foo foo foo foo foo foo"
var fooAttrString = NSMutableAttributedString(string: fooString)
let selectedRange: NSRange = NSMakeRange(12,6)

// attr1: strikethrough over range (12,6) (12..<18)
var myRange = NSRange(location: 12, length: 6)
let strikeThroughAttr = [ NSStrikethroughStyleAttributeName: 2 ]
fooAttrString.addAttributes(strikeThroughAttr, range: myRange)

// attr2: font over range (16,8) (16..<24)
myRange = NSRange(location: 16, length: 8)
let fontAttr = [ NSFontAttributeName: UIFont(name:"HelveticaNeue", size: 20)! ]
fooAttrString.addAttributes(fontAttr, range: myRange)

/* Example usage: extension */
let attributesOverRanges = fooAttrString.getAttributes()
for (rng, attributes) in attributesOverRanges {
    print("Attributes over range \(rng):")
    attributes.forEach { print("\t\([=12=].0) = \([=12=].1)") }
}
/* Attributes over range (0,12):
   Attributes over range (12,4):
       NSStrikethrough = 2
   Attributes over range (16,2):
       NSFont = <UICTFont: 0x7fcfd860f0b0> font-family: "Helvetica Neue"; font-weight: normal; font-style: normal; font-size: 20.00pt
       NSStrikethrough = 2
   Attributes over range (18,6):
       NSFont = <UICTFont: 0x7fcfd860f0b0> font-family: "Helvetica Neue"; font-weight: normal; font-style: normal; font-size: 20.00pt
   Attributes over range (24,3):                       */

将上述应用到您的 `UITextView` 实例，特别是属性 `textStorage`

现在，UITextView 的 textStorage 属性是 NSTextStorage 类型，它是 NSMutableAttributedString 的（半具体）子类，它本身是 NSAttributedString 的子类。因此，上面的扩展 getAttributes() 将可以访问，并且在 NSTextStorage 个实例上也能正常工作，例如textView.textStorage 在你的问题中。

因此，使用与上述相同的扩展，我们设置了一个类似的示例，但是对于具有属性 textStorage 属性.

的 UITextView

/* Example setup: UITextView:s 'textStorage' (type NSTextStorage) */
let fooString = "foo foo foo foo foo foo foo"

// attr1: strikethrough over range (12,6) (12..<18)
let strikeThroughRng = NSRange(location: 12, length: 6)
let strikeThroughAttr = [ NSStrikethroughStyleAttributeName: 2 ]

// attr2: font over range (16,8) (16..<24)
let fontRng = NSRange(location: 16, length: 8)
let fontAttr = [ NSFontAttributeName: UIFont(name:"HelveticaNeue", size: 20)! ]

// create text view and set attributes
let textView = UITextView()
textView.text = fooString
textView.textStorage.beginEditing()
textView.textStorage.addAttributes(strikeThroughAttr, range: strikeThroughRng)
textView.textStorage.addAttributes(fontAttr, range: fontRng)
textView.textStorage.endEditing()

用法示例，扩展名：

/* Example usage: extension (uses first version above) */
let attributesOverRanges = textView.textStorage.getAttributes()
for (rng, attributes) in attributesOverRanges {
    print("Attributes over range \(rng):")
    attributes.forEach { print("\t\([=14=].0) = \([=14=].1)") }
}
/* Attributes over range (0,12):
       NSOriginalFont = <UICTFont: 0x7ff610d88e20> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 12.00pt
       NSFont = <UICTFont: 0x7ff610d88e20> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 12.00pt
   Attributes over range (12,4):
       NSOriginalFont = <UICTFont: 0x7ff610d88e20> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 12.00pt
       NSFont = <UICTFont: 0x7ff610d88e20> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 12.00pt
       NSStrikethrough = 2
   Attributes over range (16,2):
       NSFont = <UICTFont: 0x7ff610d80820> font-family: "Helvetica Neue"; font-weight: normal; font-style: normal; font-size: 20.00pt
       NSStrikethrough = 2
   Attributes over range (18,6):
       NSFont = <UICTFont: 0x7ff610d80820> font-family: "Helvetica Neue"; font-weight: normal; font-style: normal; font-size: 20.00pt
   Attributes over range (24,3):
       NSOriginalFont = <UICTFont: 0x7ff610d88e20> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 12.00pt
       NSFont = <UICTFont: 0x7ff610d88e20> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 12.00pt */

正如预期的那样，我们看到与上面 NSAttributedString 示例相同的结果，区别在于 textView.textStorage 包含一些默认属性（NSFont、NSOriginalFont ).

在属性字符串中搜索第一次出现的给定属性和属性值

如果您愿意，您还可以编写一个扩展来搜索属性字符串以查找特定属性和值，使用 NSAttributedString

的 attribute(attrName:atIndex:effectiveRange:) 方法

Declaration:
func attribute(attrName: String, atIndex location: Int, 
               effectiveRange range: NSRangePointer) -> AnyObject?
Description:

Returns the value for an attribute with a given name of the character at a given index, and by reference the range over which the attribute applies.

Return value:

The value for the attribute named attributeName of the character at index, or nil if there is no such attribute.

更具体地说，创建一个扩展

为给定值（例如 2）搜索给定属性（例如 NSFontAttributeName）的属性字符串，并且 return 范围（NSRange）对于给定属性字符串中此类属性部分的第一次出现，或 nil，如果可以找到 none。

NSAttributedString扩展如下

/* find the range of (the first occurence of) a given 
   attribute 'attrName' for a given value 'forValue'. */
extension NSAttributedString {

    func findRangeOfAttribute(attrName: String, forValue value: AnyObject) -> NSRange? {

        var rng = NSRange()

        /* Is attribute (with given value) in range 0...X ? */
        if let val = self.attribute(attrName, atIndex: 0, effectiveRange: &rng) where val.isEqual(value) { return rng }

        /* If not, is attribute (with given value) anywhere in range X+1..<end? */
        else if
            let from = rng.toRange()?.endIndex where from < self.length - 1,
            let val = self.attribute(attrName, atIndex: from, effectiveRange: &rng) where val.isEqual(value) { return rng }

        /* if none of the above, return nil */
        return nil
    }
}

用法示例：

/* Example */
let fooString = "foo foo foo foo foo foo foo"
var fooAttrString = NSMutableAttributedString(string: fooString)
let selectedRange: NSRange  = NSMakeRange(12,6)

let myRange = NSRange(location: 12, length: 6)
let attr = [ NSStrikethroughStyleAttributeName: 2 ]
fooAttrString.addAttributes(attr, range: myRange)

/* Example usage: extension */
if let rngOfFirstStrikethrough = fooAttrString.findRangeOfAttribute(NSStrikethroughStyleAttributeName, forValue: 2) {
    print(rngOfStrikethrough) // (12,6)
}

如何使用 TextKit（不是 NSAttributedStrings）在 UITextView 中获取属性信息

how to get Attributed-Informations in UITextView with TextKit (not NSAttributedStrings)

xcode

nsattributedstring

nsfont

swift2

唯一属性范围的离散化（w.r.t。left/right 这些的相邻范围）

将上述应用到您的 `UITextView` 实例，特别是属性 `textStorage`

在属性字符串中搜索第一次出现的给定属性和属性值

如何使用 TextKit（不是 NSAttributedStrings）在 UITextView 中获取属性信息

how to get Attributed-Informations in UITextView with TextKit (not NSAttributedStrings)

xcode

nsattributedstring

nsfont

swift2

唯一属性范围的离散化（w.r.t。left/right 这些的相邻范围）

将上述应用到您的 UITextView 实例，特别是 属性 textStorage

在属性字符串中搜索第一次出现的给定属性和属性值

将上述应用到您的 `UITextView` 实例，特别是属性 `textStorage`