我会使用这个扩展，以灵活和模仿其他集合如何做到这一点:

extension String {
    func filter(pred: Character -> Bool) -> String {
        var res = String()
        for c in self.characters {
            if pred(c) {
                res.append(c)
            }
        }
        return res
    }
}

"this is a String".filter { $0 != Character(" ") } // "thisisaString"

class SpaceRemover
{
    func SpaceRemover(str :String)->String
    {
        var array = Array(str)
        var i = array.count
        while(array.last == " ")
        {
            var array1 = [Character]()
            for item in  0...i - 1
            {
                array1.append(array[item])
            }
            i = i - 1
            array = array1
            print(array1)
            print(array)

        }

        var arraySecond = array
        var j = arraySecond.count

        while(arraySecond.first == " ")
        {
            var array2 = [Character]()
            if j > 1
            {
                for item in 1..<j
                {
                    array2.append(arraySecond[item])
                }
            }
            j = j - 1
            arraySecond = array2
            print(array2)
            print(arraySecond)

        }
        print(arraySecond)
        return String(arraySecond)
    }
}

你也可以试试这个

   let updatedString = searchedText?.stringByReplacingOccurrencesOfString(" ", withString: "-")

斯威夫特5 + 从字符串的前缀(开始)删除所有空白，你可以使用类似的后缀/字符串的结束

 extension String {
    func deletingPrefix(_ prefix: String) -> String {
      guard self.hasPrefix(prefix) else { return self }
      return String(self.dropFirst(prefix.count))
    }
    
    func removeWhitespacePrefix() -> String {
     let prefixString = self.prefix(while: { char in
        return char == " "
      })
      return self.deletingPrefix(String(prefixString))
    }
  }

斯威夫特4

使用正则表达式的最佳情况:

" this is    wrong contained teee xt     "
    .replacingOccurrences(of: "^\\s+|\\s+|\\s+$", 
                          with: "", 
                          options: .regularExpression)

// thisiswrongcontainedteeext

如果有人从字符串中删除额外的空格，例如= "这是演示文本，请在单词之间删除额外的空格。"

你可以在Swift 4中使用这个函数。

func removeSpace(_ string: String) -> String{
    var str: String = String(string[string.startIndex])
    for (index,value) in string.enumerated(){
        if index > 0{
            let indexBefore = string.index(before: String.Index.init(encodedOffset: index))
            if value == " " && string[indexBefore] == " "{
            }else{
                str.append(value)
            }
        }
    }
    return str
}

结果是

"This is the demo text remove extra space between the words."