string = string.filter ({!" ".contains($0) })

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"

删除字符串中的所有空格:

let space_removed_string = (yourstring?.components(separatedBy: " ").joined(separator: ""))!

extension String {

    var removingWhitespaceAndNewLines: String {
        return removing(.whitespacesAndNewlines)
    }

    func removing(_ forbiddenCharacters: CharacterSet) -> String {
        return String(unicodeScalars.filter({ !forbiddenCharacters.contains($0) }))
    }
}

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)
    }
}

删除开头和结尾的空格:

let trimmedString = string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())

Swift 3 / Swift 4:

let trimmedString = string.trimmingCharacters(in: .whitespaces)