Swift NSAttributedString修剪

Question

我想在我的NSAttributedString（修剪它）的前面和末尾骑上白色空间。我不能简单地将其转换为字符串并进行修剪，因为其中有图像（附件）。我该怎么做？

Answer 1

创建NSAttributedString的扩展，如下所示。

extension NSAttributedString {
     public func attributedStringByTrimmingCharacterSet(charSet: NSCharacterSet) -> NSAttributedString {
         let modifiedString = NSMutableAttributedString(attributedString: self)
         modifiedString.trimCharactersInSet(charSet)
         return NSAttributedString(attributedString: modifiedString)
     }
}

extension NSMutableAttributedString {
     public func trimCharactersInSet(charSet: NSCharacterSet) {
         var range = (string as NSString).rangeOfCharacterFromSet(charSet)

         // Trim leading characters from character set.
         while range.length != 0 && range.location == 0 {
             replaceCharactersInRange(range, withString: "")
             range = (string as NSString).rangeOfCharacterFromSet(charSet)
         }

         // Trim trailing characters from character set.
         range = (string as NSString).rangeOfCharacterFromSet(charSet, options: .BackwardsSearch)
         while range.length != 0 && NSMaxRange(range) == length {
             replaceCharactersInRange(range, withString: "")
             range = (string as NSString).rangeOfCharacterFromSet(charSet, options: .BackwardsSearch)
         }
     }
}

并在viewController中使用你想要使用的地方。像这样

let attstring = NSAttributedString(string: "this is test message. Please wait.                   ")
let result = attstring.attributedStringByTrimmingCharacterSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())

Answer 2

这甚至可以在文本中使用表情符号

extension NSAttributedString {

    /** Will Trim space and new line from start and end of the text */
    public func trimWhiteSpace() -> NSAttributedString {
        let invertedSet = CharacterSet.whitespacesAndNewlines.inverted
        let startRange = string.utf16.description.rangeOfCharacter(from: invertedSet)
        let endRange = string.utf16.description.rangeOfCharacter(from: invertedSet, options: .backwards)
        guard let startLocation = startRange?.upperBound, let endLocation = endRange?.lowerBound else {
            return NSAttributedString(string: string)
        }

        let location = string.utf16.distance(from: string.startIndex, to: startLocation) - 1
        let length = string.utf16.distance(from: startLocation, to: endLocation) + 2
        let range = NSRange(location: location, length: length)
        return attributedSubstring(from: range)
    }

}

用法

let attributeString = NSAttributedString(string: "\n\n\n     Hi 👋 👩‍👩‍👧👩‍👩‍👦‍👦👩‍👩‍👧‍👧👨‍👨‍👦👩‍👦👨‍👨‍👧‍👧👨‍👨‍👦‍👦👨‍👨‍👧‍👦👩‍👧‍👦👩‍👦‍👦👩‍👧‍👧👨‍👦 buddy.              ")
let result = attributeString.trimWhiteSpace().string // Hi 👋 👩‍👩‍👧👩‍👩‍👦‍👦👩‍👩‍👧‍👧👨‍👨‍👦👩‍👦👨‍👨‍👧‍👧👨‍👨‍👦‍👦👨‍👨‍👧‍👦👩‍👧‍👦👩‍👦‍👦👩‍👧‍👧👨‍👦 buddy.

Answer 3

我做了一个快速的3实现，以防万一有人感兴趣：

/**
 Trim an attributed string. Can for example be used to remove all leading and trailing spaces and line breaks.
 */
public func attributedStringByTrimmingCharactersInSet(set: CharacterSet) -> NSAttributedString {
    let invertedSet = set.inverted
    let rangeFromStart = string.rangeOfCharacter(from: invertedSet)
    let rangeFromEnd = string.rangeOfCharacter(from: invertedSet, options: .backwards)
    if let startLocation = rangeFromStart?.upperBound, let endLocation = rangeFromEnd?.lowerBound {
        let location = string.distance(from: string.startIndex, to: startLocation) - 1
        let length = string.distance(from: startLocation, to: endLocation) + 2
        let newRange = NSRange(location: location, length: length)
        return self.attributedSubstring(from: newRange)
    } else {
        return NSAttributedString()
    }
}

Answer 4

斯威夫特4及以上

extension NSMutableAttributedString {

    func trimmedAttributedString() -> NSAttributedString {
        let invertedSet = CharacterSet.whitespacesAndNewlines.inverted
        let startRange = string.rangeOfCharacter(from: invertedSet)
        let endRange = string.rangeOfCharacter(from: invertedSet, options: .backwards)
        guard let startLocation = startRange?.upperBound, let endLocation = endRange?.lowerBound else {
            return NSAttributedString(string: string)
        }
        let location = string.distance(from: string.startIndex, to: startLocation) - 1
        let length = string.distance(from: startLocation, to: endLocation) + 2
        let range = NSRange(location: location, length: length)
        return attributedSubstring(from: range)
    }
}

使用：

let string = "This is string with some space in the end.     "
let attributedText = NSMutableAttributedString(string: string).trimmedAttributedString()

Answer 5

Swift 3.2版本：

extension NSAttributedString {
    public func trimmingCharacters(in characterSet: CharacterSet) -> NSAttributedString {
        let modifiedString = NSMutableAttributedString(attributedString: self)
        modifiedString.trimCharacters(in: characterSet)
        return NSAttributedString(attributedString: modifiedString)
    }
}

extension NSMutableAttributedString {
    public func trimCharacters(in characterSet: CharacterSet) {
        var range = (string as NSString).rangeOfCharacter(from: characterSet)

        // Trim leading characters from character set.
        while range.length != 0 && range.location == 0 {
            replaceCharacters(in: range, with: "")
            range = (string as NSString).rangeOfCharacter(from: characterSet)
        }

        // Trim trailing characters from character set.
        range = (string as NSString).rangeOfCharacter(from: characterSet, options: .backwards)
        while range.length != 0 && NSMaxRange(range) == length {
            replaceCharacters(in: range, with: "")
            range = (string as NSString).rangeOfCharacter(from: characterSet, options: .backwards)
        }
    }
}

Answer 6

以下代码适用于您的要求。

var attString: NSAttributedString = NSAttributedString(string: " this is att string")

let trimmedString = attString.string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())