swift String extension

最新推荐文章于 2021-06-04 11:08:08 发布
转载最新推荐文章于 2021-06-04 11:08:08 发布 · 1.3k 阅读
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本文介绍了Swift中字符串处理的一些实用方法，包括查找、替换、分割、拼接、大小写转换、去除空格等基本操作，以及一些进阶功能如驼峰命名、首字母大写等。
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//
//  SwiftString.swift
//  SwiftString
//
//  Created by Andrew Mayne on 30/01/2016.
//  Copyright © 2016 Red Brick Labs. All rights reserved.
//

import Foundation

public extension String {
    
    ///  Finds the string between two bookend strings if it can be found.
    ///
    ///  - parameter left:  The left bookend
    ///  - parameter right: The right bookend
    ///
    ///  - returns: The string between the two bookends, or nil if the bookends cannot be found, the bookends are the same or appear contiguously.
    func between(left: String, _ right: String) -> String? {
        guard
            let leftRange = rangeOfString(left), rightRange = rangeOfString(right, options: .BackwardsSearch)
            where left != right && leftRange.endIndex != rightRange.startIndex
            else { return nil }
        
        return self[leftRange.endIndex...rightRange.startIndex.predecessor()]
        
    }
    
    // https://gist.github.com/stevenschobert/540dd33e828461916c11
    func camelize() -> String {
        let source = clean(with: " ", allOf: "-", "_")
        if source.characters.contains(" ") {
            let first = source.substringToIndex(source.startIndex.advancedBy(1))
            let cammel = NSString(format: "%@", (source as NSString).capitalizedString.stringByReplacingOccurrencesOfString(" ", withString: "", options: [], range: nil)) as String
            let rest = String(cammel.characters.dropFirst())
            return "\(first)\(rest)"
        } else {
            let first = (source as NSString).lowercaseString.substringToIndex(source.startIndex.advancedBy(1))
            let rest = String(source.characters.dropFirst())
            return "\(first)\(rest)"
        }
    }
    
    func capitalize() -> String {
        return capitalizedString
    }
    
    func contains(substring: String) -> Bool {
        return rangeOfString(substring) != nil
    }
    
    func chompLeft(prefix: String) -> String {
        if let prefixRange = rangeOfString(prefix) {
            if prefixRange.endIndex >= endIndex {
                return self[startIndex..<prefixRange.startIndex]
            } else {
                return self[prefixRange.endIndex..<endIndex]
            }
        }
        return self
    }
    
    func chompRight(suffix: String) -> String {
        if let suffixRange = rangeOfString(suffix, options: .BackwardsSearch) {
            if suffixRange.endIndex >= endIndex {
                return self[startIndex..<suffixRange.startIndex]
            } else {
                return self[suffixRange.endIndex..<endIndex]
            }
        }
        return self
    }
    
    func collapseWhitespace() -> String {
        let components = componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).filter { !$0.isEmpty }
        return components.joinWithSeparator(" ")
    }
    
    func clean(with with: String, allOf: String...) -> String {
        var string = self
        for target in allOf {
            string = string.stringByReplacingOccurrencesOfString(target, withString: with)
        }
        return string
    }
    
    func count(substring: String) -> Int {
        return componentsSeparatedByString(substring).count-1
    }
    
    func endsWith(suffix: String) -> Bool {
        return hasSuffix(suffix)
    }
    
    func ensureLeft(prefix: String) -> String {
        if startsWith(prefix) {
            return self
        } else {
            return "\(prefix)\(self)"
        }
    }
    
    func ensureRight(suffix: String) -> String {
        if endsWith(suffix) {
            return self
        } else {
            return "\(self)\(suffix)"
        }
    }
    
    func indexOf(substring: String) -> Int? {
        if let range = rangeOfString(substring) {
            return startIndex.distanceTo(range.startIndex)
        }
        return nil
    }
    
    func initials() -> String {
        let words = self.componentsSeparatedByString(" ")
        return words.reduce(""){$0 + $1[0...0]}
    }
    
    func initialsFirstAndLast() -> String {
        let words = self.componentsSeparatedByString(" ")
        return words.reduce("") { ($0 == "" ? "" : $0[0...0]) + $1[0...0]}
    }
    
    func isAlpha() -> Bool {
        for chr in characters {
            if (!(chr >= "a" && chr <= "z") && !(chr >= "A" && chr <= "Z") ) {
                return false
            }
        }
        return true
    }
    
    func isAlphaNumeric() -> Bool {
        let alphaNumeric = NSCharacterSet.alphanumericCharacterSet()
        return componentsSeparatedByCharactersInSet(alphaNumeric).joinWithSeparator("").length == 0
    }
    
    func isEmpty() -> Bool {
        return self.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).length == 0
    }
    
    func isNumeric() -> Bool {
        if let _ = NSNumberFormatter().numberFromString(self) {
            return true
        }
        return false
    }
    
    func join<S: SequenceType>(elements: S) -> String {
        return elements.map{String($0)}.joinWithSeparator(self)
    }
    
    func latinize() -> String {
        return self.stringByFoldingWithOptions(.DiacriticInsensitiveSearch, locale: NSLocale.currentLocale())
    }
    
    func lines() -> [String] {
        return self.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet())
    }
    
    var length: Int {
        get {
            return self.characters.count
        }
    }
    
    func pad(n: Int, _ string: String = " ") -> String {
        return "".join([string.times(n), self, string.times(n)])
    }
    
    func padLeft(n: Int, _ string: String = " ") -> String {
        return "".join([string.times(n), self])
    }
    
    func padRight(n: Int, _ string: String = " ") -> String {
        return "".join([self, string.times(n)])
    }
    
    func slugify(withSeparator separator: Character = "-") -> String {
        let slugCharacterSet = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789\(separator)")
        return latinize()
            .lowercaseString
            .componentsSeparatedByCharactersInSet(slugCharacterSet.invertedSet)
            .filter { $0 != "" }
            .joinWithSeparator(String(separator))
    }
    
    func split(separator: Character) -> [String] {
        return characters.split{$0 == separator}.map(String.init)
    }
    
    func startsWith(prefix: String) -> Bool {
        return hasPrefix(prefix)
    }
    
    func stripPunctuation() -> String {
        return componentsSeparatedByCharactersInSet(.punctuationCharacterSet())
            .joinWithSeparator("")
            .componentsSeparatedByString(" ")
            .filter { $0 != "" }
            .joinWithSeparator(" ")
    }
    
    func times(n: Int) -> String {
        return (0..<n).reduce("") { $0.0 + self }
    }
    
    func toFloat() -> Float? {
        if let number = NSNumberFormatter().numberFromString(self) {
            return number.floatValue
        }
        return nil
    }
    
    func toInt() -> Int? {
        if let number = NSNumberFormatter().numberFromString(self) {
            return number.integerValue
        }
        return nil
    }
    
    func toDouble(locale: NSLocale = NSLocale.systemLocale()) -> Double? {
        let nf = NSNumberFormatter()
        nf.locale = locale
        if let number = nf.numberFromString(self) {
            return number.doubleValue
        }
        return nil
    }
    
    func toBool() -> Bool? {
        let trimmed = self.trimmed().lowercaseString
        if trimmed == "true" || trimmed == "false" {
            return (trimmed as NSString).boolValue
        }
        return nil
    }
    
    func toDate(format: String = "yyyy-MM-dd") -> NSDate? {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = format
        return dateFormatter.dateFromString(self)
    }
    
    func toDateTime(format: String = "yyyy-MM-dd HH:mm:ss") -> NSDate? {
        return toDate(format)
    }
    
    func trimmedLeft() -> String {
        if let range = rangeOfCharacterFromSet(NSCharacterSet.whitespaceAndNewlineCharacterSet().invertedSet) {
            return self[range.startIndex..<endIndex]
        }
        return self
    }
    
    func trimmedRight() -> String {
        if let range = rangeOfCharacterFromSet(NSCharacterSet.whitespaceAndNewlineCharacterSet().invertedSet, options: NSStringCompareOptions.BackwardsSearch) {
            return self[startIndex..<range.endIndex]
        }
        return self
    }
    
    func trimmed() -> String {
        return self.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
    }
    
    subscript(r: Range<Int>) -> String {
        get {
            let startIndex = self.startIndex.advancedBy(r.startIndex)
            let endIndex = self.startIndex.advancedBy(r.endIndex - r.startIndex)
            return self[startIndex..<endIndex]
        }
    }
    
    func substring(startIndex: Int, length: Int) -> String {
        let start = self.startIndex.advancedBy(startIndex)
        let end = self.startIndex.advancedBy(startIndex + length)
        return self[start..<end]
    }
    
    subscript(i: Int) -> Character {
        get {
            let index = self.startIndex.advancedBy(i)
            return self[index]
        }
    }    
}