Swift 3.1獲取兩個字符之間的範圍？

Question

我明顯做錯了什麼，因爲這更新了我花了很長時間去做以下事情:(遊戲場代碼在下面）。

注：雨燕3.1〜

我只是想從piz(123)zazz

let aString = "piz(123)zazz" 

let startBracket: Character = "(" 
if let idx1 = aString.characters.index(of: startBracket) { 
    let pos1 = aString.characters.distance(from: aString.startIndex, to: idx1) 
    print("Found \(startBracket) at position \(pos1)") 
} 
else { 
    print("Not found") 
} 

let endBracket: Character = ")" 
if let idx2 = aString.characters.index(of: endBracket) { 
    let pos2 = aString.characters.distance(from: aString.startIndex, to: idx2) 
    print("Found \(startBracket) at position \(pos2)") 
} 
else { 
    print("Not found") 
} 

let range = pos1..<pos2 // << this is not working, I give up!!! 

let result_1 = aString.substring(with: range) 

Answer 1

這是很容易：

• 開始指數是(串

• 範圍內的upperBound最終指數是)範圍的串

  在lowerBound

  let aString = "piz(123)zazz" 
  
  if let openParenthesisRange = aString.range(of: "("), 
      let closeParenthesisRange = aString.range(of: ")", range: openParenthesisRange.upperBound..<aString.endIndex) { 
  
      let range = openParenthesisRange.upperBound..<closeParenthesisRange.lowerBound 
      let result = aString.substring(with: range) 
      print(result) 
  } 
  else { 
      print("Not found") 
  } 
  

---

或者正則表達式，它更多的代碼，但它更靈活

let string = "piz(123)zazz" 

let pattern = "\\((\\d+)\\)" // searches for 0 ore more digits between parentheses 

do { 
    let regex = try NSRegularExpression(pattern: pattern) 
    if let match = regex.firstMatch(in: string, range: NSRange(location: 0, length: string.utf16.count)) { 
     let range = match.rangeAt(1) 
     let start = string.index(string.startIndex, offsetBy: range.location) 
     let end = string.index(start, offsetBy: range.length) 
     print(string.substring(with: start..<end)) 
    } else { 
     print("Not Found") 
    } 
} catch { 
    print("Regex Error:", error) 
} 

Answer 2

你pos1和pos2得到123出超出範圍，當你試圖使用。它們都是在if塊內定義的，它們的範圍本身就在那裏結束。

我會建議在頂部聲明它們使它們在範圍內。

let aString = "piz(123)zazz" 
let pos1: Int? // You don't need optional here but I prefer it 
let pos2: Int? 
. 
. 
. 
if let p1 = pos1, p2 = pos2 { // Optional Chaining 
    let range = pos1..<pos2 
}