Swift截取HTML中的所有图片url

在Swift中，要从HTML格式的String中截取出所有的img的所有图片url，要截取的url就要匹配url，需要用到正则表达式。

Swift使用正则截取字符串的方法：

extension String {

    /**
     根据 正则表达式 截取字符串

     - parameter regex: 正则表达式

     - returns: 字符串数组
     */
    public func matchesForRegex(regex: String) -> [String]? {

        do {
            let regularExpression = try NSRegularExpression(pattern: regex, options: [])
            let range = NSMakeRange(0, self.characters.count)
            let results = regularExpression.matchesInString(self, options: [], range: range)
            let string = self as NSString
            return results.map { string.substringWithRange($0.range)}
        } catch {
            return nil
        }
    }
}

匹配img标签的正则表达式为：

<img\b(?=\s)(?=(?:[^>=]|='[^']*'|="[^"]*"|=[^'"][^\s>]*)*?\ssrc=['"]([^"]*)['"]?)(?:[^>=]|='[^']*'|="[^"]*"|=[^'"\s]*)*"\s?\/?>

在swift中的正则表达式书写为：

let regex = "<img\\b(?=\\s)(?=(?:[^>=]|='[^']*'|=\"[^\"]*\"|=[^'\"][^\\s>]*)*?\\ssrc=['\"]([^\"]*)['\"]?)(?:[^>=]|='[^']*'|=\"[^\"]*\"|=[^'\"\\s]*)*\"\\s?\\/?>"

使用案例：

let string = "图片1<div><img src=\"http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg\" alt=\"Gravatar\"><br></div><div>图片2</div><div><img src=\"http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg\" alt=\"Gravatar\"><br></div><div><br></div><div>图片3</div><div><img src=\"http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg\" alt=\"Gravatar\"><br></div><div><br></div>"

// 截取img标签
let resultItems = string.matchesForRegex(regex)

截取得到的resultItems为:

 ["<img src=\"http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg\" alt=\"Gravatar\">", 
 "<img src=\"http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg\" alt=\"Gravatar\">",
  "<img src=\"http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg\" alt=\"Gravatar\">"]

如果单单只是截取img的url地址，使用的正则表达式为：

(http[^\s]+(jpg|jpeg|png|tiff)\b)

在Swift中书写为：

let regex = "(http[^\\s]+(jpg|jpeg|png|tiff)\\b)"

使用案例：

// 截取所有img url
let resultItems = string.matchesForRegex(regex)

结果为：

[“http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg“, “http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg“, “http://cms-bucket.nosdn.127.net/catchpic/C/C7/C7643B52B98D04979AA173C6D6219958.jpg“]

Swift截取HTML中的所有图片url

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