如何检查字符串是否只包含[0-9]和.
我希望从字符串中删除所有其他符号。如果用户输入任何字符串
var anyString:String = “3f00b6r.beAwes0me4me”
我想从中提取所有数字（包括一个.（如果存在）），并删除所有其他字符。
var myDouble:Double = 3006.04
知道怎么做的人？
您可以使用NSRegularExpression，如下所示：
// First set up error for checking
var error:NSError?
// Create regular expression pattern to search for numbers one digit in length or longer
let regexString = NSRegularExpression(pattern: "[0-9]{1,}.[0-9]{1,}|[0-9]{1,}", options: nil, error: &error)
// example string
let string = "find the number 10.19"
// get the string length
let strLength = count(string)
// To return the result first of all obtain the range of the first match if there is one, if let used here because NSRegularExpression returns an optional (we could of checked earlier, but I didn't)
if let rangeOfFirstMatch = regexString?.rangeOfFirstMatchInString(string, options: nil, range: NSMakeRange(0, strLength))
{
// if a range has been found that isn't equal to NSNotFound then build a range for the found string
if !NSEqualRanges(rangeOfFirstMatch, NSMakeRange(NSNotFound, 0)) {
advance(string.startIndex, rangeOfFirstMatch.length)
let r = Range(start: advance(string.startIndex, rangeOfFirstMatch.location), end: advance(string.startIndex, rangeOfFirstMatch.location+rangeOfFirstMatch.length))
// return the value
let substringForFirstMatch = string.substringWithRange(r)
println("Here's your match: (substringForFirstMatch)")
}
}
还有String.stringByTrimmingCharactersInSet()，它会更干净、更快，但没有那么通用。例如，如果你这样做，上面的字符串也会被返回：
let set = NSMutableCharacterSet.alphanumericCharacterSet()
set.addCharactersInString(" ")
set.removeCharactersInString("0123456789.")
string.stringByTrimmingCharactersInSet(set)
但是，如果字符串更改为"查找数字？？…10.19…"，则字符串ByTrimingCharactersISet（）会让您失望并返回"??...10.19...."，而正则表达式版本会保持不变。
为了让事情变得更容易，字符串扩展可以这样写，用于在Double或Int:类型的字符串中返回多个数字
extension String {
func stringsMatchingRegularExpression(expression exp:String, error err:NSErrorPointer) -> [String]? {
var strArray:[String]?
var rangeArray:[NSRange]?
let strLength = count(self)
var startOfRange = 0
if let regexString = NSRegularExpression(pattern: exp, options: nil, error: err) {
while startOfRange <= strLength {
let rangeOfMatch = regexString.rangeOfFirstMatchInString(self, options: nil, range: NSMakeRange(startOfRange, strLength-startOfRange))
if let rArray = rangeArray {
rangeArray = rArray + [rangeOfMatch]
}
else {
rangeArray = [rangeOfMatch]
}
startOfRange = rangeOfMatch.location+rangeOfMatch.length
}
if let ranArr = rangeArray {
for r in ranArr {
if !NSEqualRanges(r, NSMakeRange(NSNotFound, 0)) {
advance(self.startIndex, r.length)
let r = Range(start: advance(self.startIndex, r.location), end: advance(string.startIndex, r.location+r.length))
// return the value
let substringForMatch = self.substringWithRange(r)
if let sArray = strArray {
strArray = sArray + [substringForMatch]
}
else {
strArray = [substringForMatch]
}
}
}
}
}
return strArray
}
}
let myString = "one number is 7.5, another is 20"
let subStringArray = myString.stringsMatchingRegularExpression(expression: "[0-9]{1,}.[0-9]{1,}|[0-9]{1,}", error: nil)
subStringArray?[0] // 7.5
subStringArray?[1] // 20
Swift 2.0扩展更新
extension String {
func stringsMatchingRegularExpression(expression exp:String) -> [String]? {
var strArray:[String]?
var rangeArray:[NSRange]?
let strLength = self.characters.count
var startOfRange = 0
do {
let regexString = try NSRegularExpression(pattern: exp, options: [])
while startOfRange <= strLength {
let rangeOfMatch = regexString.rangeOfFirstMatchInString(self, options: [], range: NSMakeRange(startOfRange, strLength-startOfRange))
if let rArray = rangeArray {
rangeArray = rArray + [rangeOfMatch]
}
else {
rangeArray = [rangeOfMatch]
}
startOfRange = rangeOfMatch.location+rangeOfMatch.length
}
if let ranArr = rangeArray {
for r in ranArr {
if !NSEqualRanges(r, NSMakeRange(NSNotFound, 0)) {
self.startIndex.advancedBy(r.length)
let r = Range(start: self.startIndex.advancedBy(r.location), end: self.startIndex.advancedBy(r.location + r.length))
// return the value
let substringForMatch = self.substringWithRange(r)
if let sArray = strArray {
strArray = sArray + [substringForMatch]
}
else {
strArray = [substringForMatch]
}
}
}
}
} catch {
}
return strArray
}
}
let myString = "one number is 7.5, another is 20"
let subStringArray = myString.stringsMatchingRegularExpression(expression: "[-+]?\d+.?\d+")
subStringArray?[0] // 7.5
subStringArray?[1] // 20
Swift 3.0扩展更新
extension String {
func stringsMatchingRegularExpression(expression exp:String) -> [String]? {
var strArray:[String]?
var rangeArray:[NSRange]?
let strLength = self.characters.count
var startOfRange = 0
do {
let regexString = try NSRegularExpression(pattern: exp, options: [])
while startOfRange <= strLength {
let rangeOfMatch = regexString.rangeOfFirstMatch(in: self, options: [], range: NSMakeRange(startOfRange, strLength-startOfRange))
if let rArray = rangeArray {
rangeArray = rArray + [rangeOfMatch]
}
else {
rangeArray = [rangeOfMatch]
}
startOfRange = rangeOfMatch.location+rangeOfMatch.length
}
if let ranArr = rangeArray {
for r in ranArr {
if !NSEqualRanges(r, NSMakeRange(NSNotFound, 0)) {
self.index(startIndex, offsetBy: r.length)
let r = self.index(startIndex, offsetBy:r.location)..<self.index(startIndex, offsetBy:r.location + r.length)
// return the value
let substringForMatch = self.substring(with: r)
if let sArray = strArray {
strArray = sArray + [substringForMatch]
}
else {
strArray = [substringForMatch]
}
}
}
}
}
catch {
// catch errors here
}
return strArray
}
}
let myString = "one number is 7.5, another is 20"
let subStringArray = myString.stringsMatchingRegularExpression(expression: "[-+]?\d+.?\d+")
subStringArray?[0] // 7.5
subStringArray?[1] // 20