从字符串优化中提取链接

Question

我从网站获取数据(HTML字符串).我想提取所有链接.我写函数(它有效),但它太慢了......

你能帮我优化一下吗？我可以使用哪些标准功能？功能逻辑:在文本中找到"http:.//"sting,然后读取字符串(购买字符)直到我不会得到"\"".

extension String {

subscript (i: Int) -> Character {
    return self[advance(self.startIndex, i)]
}

subscript (i: Int) -> String {
    return String(self[i] as Character)
}

subscript (r: Range<Int>) -> String {
    return substringWithRange(Range(start: advance(startIndex, r.startIndex), end: advance(startIndex, r.endIndex)))
}}



func extractAllLinks(text:String) -> Array<String>{
var stringArray = Array<String>()
var find = "http://" as String

for (var i = countElements(find); i<countElements(text); i++)
{
    var ch:Character = text[i - Int(countElements(find))]
    if (ch == find[0])
    {
        var j = 0
        while (ch == find[j])
        {
            var ch2:Character = find[j]
            if(countElements(find)-1 == j)
            {
                break
            }
            j++
            i++
            ch = text[i - Int(countElements(find))]
        }

        i -= j
        if (j == (countElements(find)-1))
        {
            var str = ""
            for (; text[i - Int(countElements(find))] != "\""; i++)
            {
                str += text[i - Int(countElements(find))]
            }
            stringArray.append(str)
        }

    }
}
return stringArray}

Answer 1

就像AdamPro13上面说的使用NSDataDetector你可以轻松获取所有URL,请看下面的代码:

let text = "http://www.google.com. http://www.bla.com"
let types: NSTextCheckingType = .Link
var error : NSError?

let detector = NSDataDetector(types: types.rawValue, error: &error)        
var matches = detector!.matchesInString(text, options: nil, range: NSMakeRange(0, count(text)))

for match in matches {
   println(match.URL!)
}

它输出:

http://www.google.com
http://www.bla.com

已更新至Swift 2.0

let text = "http://www.google.com. http://www.bla.com"
let types: NSTextCheckingType = .Link

let detector = try? NSDataDetector(types: types.rawValue)

guard let detect = detector else {
   return
}

let matches = detect.matchesInString(text, options: .ReportCompletion, range: NSMakeRange(0, text.characters.count))

for match in matches {
    print(match.URL!)
}

记得guard在上面的例子中使用它必须在函数或循环中的语句.

我希望这有帮助.

Answer 2

这就是Swift 4.0的答案

let text = "http://www.google.com. http://www.bla.com"
let types: NSTextCheckingResult.CheckingType = .link

let detector = try? NSDataDetector(types: types.rawValue)

guard let detect = detector else {
    return
}

let matches = detect.matches(in: content, options: .reportCompletion, range: NSMakeRange(0, content.count))

for match in matches {
    print(match.url!)
}

Answer 3

细节

• 斯威夫特 5.2、Xcode 11.4 (11E146)

解决方案

// MARK: DataDetector

class DataDetector {

    private class func _find(all type: NSTextCheckingResult.CheckingType,
                             in string: String, iterationClosure: (String) -> Bool) {
        guard let detector = try? NSDataDetector(types: type.rawValue) else { return }
        let range = NSRange(string.startIndex ..< string.endIndex, in: string)
        let matches = detector.matches(in: string, options: [], range: range)
        loop: for match in matches {
            for i in 0 ..< match.numberOfRanges {
                let nsrange = match.range(at: i)
                let startIndex = string.index(string.startIndex, offsetBy: nsrange.lowerBound)
                let endIndex = string.index(string.startIndex, offsetBy: nsrange.upperBound)
                let range = startIndex..<endIndex
                guard iterationClosure(String(string[range])) else { break loop }
            }
        }
    }

    class func find(all type: NSTextCheckingResult.CheckingType, in string: String) -> [String] {
        var results = [String]()
        _find(all: type, in: string) {
            results.append($0)
            return true
        }
        return results
    }

    class func first(type: NSTextCheckingResult.CheckingType, in string: String) -> String? {
        var result: String?
        _find(all: type, in: string) {
            result = $0
            return false
        }
        return result
    }
}

// MARK: String extension

extension String {
    var detectedLinks: [String] { DataDetector.find(all: .link, in: self) }
    var detectedFirstLink: String? { DataDetector.first(type: .link, in: self) }
    var detectedURLs: [URL] { detectedLinks.compactMap { URL(string: $0) } }
    var detectedFirstURL: URL? {
        guard let urlString = detectedFirstLink else { return nil }
        return URL(string: urlString)
    }
}

用法

let text = """
Lorm Ipsum is simply dummy text of the printing and typesetting industry. apple.com/ Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. http://gooogle.com. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. yahoo.com It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
"""

print(text.detectedLinks)
print(text.detectedFirstLink)
print(text.detectedURLs)
print(text.detectedFirstURL)

控制台输出

["apple.com/", "http://gooogle.com", "yahoo.com"]
Optional("apple.com/")
[apple.com/, http://gooogle.com, yahoo.com]
Optional(apple.com/)