ios - 用字典中的正确值替换字符串中匹配的正则表达式值

Question

我有一个字符串

var text = "the {animal} jumped over the {description} fox"

和字典

var dictionary = ["animal":"dog" , "description", "jumped"]

我正在编写一个函数，用字典中的适当值替换花括号中的文本。我想为此使用正则表达式。

 //alpha numeric characters, - and _
 let regex = try NSRegularExpression(pattern: "{[a-zA-Z0-9-_]}", options: .caseInsensitive)

var text = "the {animal} jumped over the {description} fox"
let all = NSRange(location: 0, length: text.count)

regex.enumerateMatches(in: text, options: [], range: all) { (checkingResult, matchingFlags, _) in
    guard let resultRange = checkingResult?.range else {
        print("error getting result range")
        return
    }
    //at this point, i was hoping that (resultRange.lowerbound, resultRange,upperBound) would be the start and end index of my regex match. 
    //so print(text[resultRange.lowerBound..<resultRange.upperBound] should give me {animal}
    //so i could get the word between the curly braces, and replace it in the sentence with it dictionary value         
}

但是快速的字符串操作让我非常困惑，这似乎行不通。

这是正确的方向吗？

谢谢

Answer 1

这是一种有效的解决方案。字符串处理更加复杂，因为您还必须处理 NSRange。

extension String {
    func format(with parameters: [String: Any]) -> String {
        var result = self

        //Handles keys with letters, numbers, underscore, and hyphen
        let regex = try! NSRegularExpression(pattern: "\\{([-A-Za-z0-9_]*)\\}", options: [])

        // Get all of the matching keys in the curly braces
        let matches = regex.matches(in: self, options: [], range: NSRange(self.startIndex..<self.endIndex, in: self))

        // Iterate in reverse to avoid messing up the ranges as the keys are replaced with the values
        for match in matches.reversed() {
            // Make sure there are two matches each
            // range 0 includes the curly braces
            // range 1 includes just the key name in the curly braces
            if match.numberOfRanges == 2 {
                // Make sure the ranges are valid (this should never fail)
                if let keyRange = Range(match.range(at: 1), in: self), let fullRange = Range(match.range(at: 0), in: self) {
                    // Get the key in the curly braces
                    let key = String(self[keyRange])
                    // Get that value from the dictionary
                    if let val = parameters[key] {
                        result.replaceSubrange(fullRange, with: "\(val)")
                    }
                }
            }
        }

        return result
    }
}

var text = "the {animal} jumped over the {description} fox"
var dictionary = ["animal":"dog" , "description": "jumped"]
print(text.format(with: dictionary))

输出:

the dog jumped over the jumped fox

如果在字典中找不到，此代码会将原始 {keyname} 保留在字符串中。根据需要调整该代码。