快速解决方案:

用法:

let txt = "        hello world     "
let txt1 = txt.trimStart() // "hello world     "
let txt2 = txt.trimEnd()   // "        hello world"

用法二:

let txt = "rr rrr rrhello world r r r r r r"
let txt1 = txt.trimStart(["r", " "]) // "hello world r r r r r r"
let txt2 = txt.trimEnd(["r", " "])   // "rr rrr rrhello world"

如果你需要移除字符串中的所有空白:

txt.replace(of: " ", to: "")

public extension String {
    func trimStart(_ char: Character) -> String {
        return trimStart([char])
    }
    
    func trimStart(_ symbols: [Character] = [" ", "\t", "\r", "\n"]) -> String {
        var startIndex = 0
        
        for char in self {
            if symbols.contains(char) {
                startIndex += 1
            }
            else {
                break
            }
        }
        
        if startIndex == 0 {
            return self
        }
        
        return String( self.substring(from: startIndex) )
    }
    
    func trimEnd(_ char: Character) -> String {
        return trimEnd([char])
    }
    
    func trimEnd(_ symbols: [Character] = [" ", "\t", "\r", "\n"]) -> String {
        var endIndex = self.count - 1
        
        for i in (0...endIndex).reversed() {
            if symbols.contains( self[i] ) {
                endIndex -= 1
            }
            else {
                break
            }
        }
        
        if endIndex == self.count {
            return self
        }
        
        return String( self.substring(to: endIndex + 1) )
    }
}

/////////////////////////
/// ACCESS TO CHAR BY INDEX
////////////////////////
extension StringProtocol {
    subscript(offset: Int) -> Character { self[index(startIndex, offsetBy: offset)] }
    subscript(range: Range<Int>) -> SubSequence {
        let startIndex = index(self.startIndex, offsetBy: range.lowerBound)
        return self[startIndex..<index(startIndex, offsetBy: range.count)]
    }
    subscript(range: ClosedRange<Int>) -> SubSequence {
        let startIndex = index(self.startIndex, offsetBy: range.lowerBound)
        return self[startIndex..<index(startIndex, offsetBy: range.count)]
    }
    subscript(range: PartialRangeFrom<Int>) -> SubSequence { self[index(startIndex, offsetBy: range.lowerBound)...] }
    subscript(range: PartialRangeThrough<Int>) -> SubSequence { self[...index(startIndex, offsetBy: range.upperBound)] }
    subscript(range: PartialRangeUpTo<Int>) -> SubSequence { self[..<index(startIndex, offsetBy: range.upperBound)] }
}

对我来说，下面这行用来删除空白。

let result = String(yourString.filter {![" ", "\t", "\n"].contains($0)})

如果你想要从前面(和后面)而不是中间删除空格，你应该使用stringByTrimmingCharactersInSet

    let dirtyString   = " First Word "
    let cleanString = dirtyString.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())

如果你想从字符串的任何地方删除空格，那么你可能需要查看stringbyreplacement…

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

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)

对于swift 3.0

import Foundation

var str = " Hear me calling"

extension String {
    var stringByRemovingWhitespaces: String {
        return components(separatedBy: .whitespaces).joined()
    }
}

str.stringByRemovingWhitespaces  // Hearmecalling