swift 类扩展 学习整理
Swift语言的类扩展是一个强大的工具，我们可以通过类扩展完成如下事情：
- 给已有的类添加计算属性和计算静态属性
- 定义新的实例方法和类方法
- 提供新的构造器
- 定义下标脚本
- 是一个已有的类型符合某个协议
示例1：给字符串String类添加下标脚本，支持索引访问
extension String
{
subscript(start:Int, length:Int) -> String
{
get{
let index1 = self.index(self.startIndex, offsetBy: start)
let index2 = self.index(index1, offsetBy: length)
return String(self[index1..<index2])
}
set{
let tmp = self
var s = ""
var e = ""
for (idx, item) in tmp.characters.enumerated() {
if(idx < start)
{
s += "\(item)"
}
if(idx >= start + length)
{
e += "\(item)"
}
}
self = s + newValue + e
}
}
subscript(index:Int) -> String
{
get{
return String(self[self.index(self.startIndex, offsetBy: index)])
}
set{
let tmp = self
self = ""
for (idx, item) in tmp.characters.enumerated() {
if idx == index {
self += "\(newValue)"
}else{
self += "\(item)"
}
}
}
}
}
extension String {
/// AES 加密后的字符串：ECB / pkcs7 / iv 不偏移
public var toAESString: String {
if let cipher = try? AES(key: App.aesKey.bytes, blockMode: ECB()).encrypt(self.bytes) {
return cipher.toHexString()
}
return ""
}
/// 将URL中的"特殊字符"转成“%3A%2F%2F”
public var urlEncoded: String {
return addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!
}
/// 将URL中的“%3A%2F%2F”转成正常字符
public var urlDecode: String {
return removingPercentEncoding!
}
/// 是否是手机号
public var isPhoneNumber: Bool {
return self.hasPrefix("1") && self.count == 11 && Int64(self) != nil
}
/// 136****3119, 星号也可设置成别的字符
public func cover(_ separator: String = "****") -> String {
guard self.isPhoneNumber else { return self }
return (self as NSString).replacingCharacters(in: NSRange(location: 3, length: 4), with: separator)
}
/// 136 9134 3119, 空格也可设置成别的
public func format(_ separator: String = " ") -> String {
guard self.isPhoneNumber else { return self }
let index1 = self.index(self.startIndex, offsetBy: 3)
let index2 = self.index(index1, offsetBy: 4)
return "\(self[self.startIndex..<index1])" + separator + "\(self[index1..<index2])" + separator + "\(self[index2..<self.endIndex])"
}
}
extension String {
/// 转成 Date，样式可修改
public func date(withFormat format: String = "yyyy-MM-dd HH:mm") -> Date? {
let dateFormatter = Date.formatter
dateFormatter.dateFormat = format
return dateFormatter.date(from: self)
}
/// 转成 JSON 对象
public func toJSON() -> Any? {
do {
return try JSON(data: data(using: .utf8)!).object
} catch {
return nil
}
}
/// 返回去掉首尾空格和新行的字符串
public func trim() -> String {
return self.trimmingCharacters(in: .whitespacesAndNewlines)
}
/// 按字数裁断字符串，用 ... 表示剩余部分
public func truncated(toLength length: Int, trailing: String? = "...") -> String {
guard 1..<count ~= length else { return self }
return self[startIndex..<index(startIndex, offsetBy: length)] + (trailing ?? "")
}
/// 给字符串添加下划线
public var underline: NSAttributedString {
return NSAttributedString(string: self, attributes: [.underlineStyle: NSUnderlineStyle.single.rawValue])
}
/// 给字符串添加删除线
public var strikethrough: NSAttributedString {
return NSAttributedString(string: self, attributes: [.strikethroughStyle: NSNumber(value: NSUnderlineStyle.single.rawValue as Int)])
}
/// 给字符串添加固定的行间距
public func addLineSpacing(_ spacing: CGFloat = 5, fontSize: CGFloat = 17) -> NSAttributedString {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = spacing
return NSAttributedString(string: self, attributes: [.font: UIFont.systemFont(ofSize: fontSize), .paragraphStyle: paragraphStyle])
}
/// 计算文本的size
///
/// - Parameters:
/// - constrainedSize: 限制的size
/// - font: 字号
/// - lineSpacing: 默认为nil，使用系统默认的行间距
/// - Returns: 计算文本的size
public func stringBoundingRect(with constrainedSize: CGSize, font: UIFont, lineSpacing: CGFloat? = nil) -> CGSize {
let attritube = NSMutableAttributedString(string: self)
let range = NSRange(location: 0, length: attritube.length)
attritube.addAttributes([NSAttributedString.Key.font: font], range: range)
if lineSpacing != nil {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = lineSpacing!
attritube.addAttribute(NSAttributedString.Key.paragraphStyle, value: paragraphStyle, range: range)
}
let rect = attritube.boundingRect(with: constrainedSize, options: [.usesLineFragmentOrigin, .usesFontLeading], context: nil)
var size = rect.size
if let currentLineSpacing = lineSpacing {
// 文本的高度减去字体高度小于等于行间距，判断为当前只有1行
let spacing = size.height - font.lineHeight
if spacing <= currentLineSpacing && spacing > 0 {
size = CGSize(width: size.width, height: font.lineHeight)
}
}
return size
}
/// 计算文本的size 可以限制行数
public func stringBoundingRect(with constrainedSize: CGSize, font: UIFont, lineSpacing: CGFloat? = nil, lines: Int) -> CGSize {
if lines < 0 {
return .zero
}
let size = stringBoundingRect(with: constrainedSize, font: font, lineSpacing: lineSpacing)
if lines == 0 {
return size
}
let currentLineSpacing = (lineSpacing == nil) ? (font.lineHeight - font.pointSize) : lineSpacing!
let maximumHeight = font.lineHeight * CGFloat(lines) + currentLineSpacing * CGFloat(lines - 1)
if size.height >= maximumHeight {
return CGSize(width: size.width, height: maximumHeight)
}
return size
}
/// base64 编码
var base64Encoded: String? {
let plainData = data(using: .utf8)
return plainData?.base64EncodedString()
}
/// base64 解码
var base64Decoded: String? {
guard let decodedData = Data(base64Encoded: self) else { return nil }
return String(data: decodedData, encoding: .utf8)
}
/// 是否包含字符
var hasLetters: Bool {
return rangeOfCharacter(from: .letters, options: .numeric, range: nil) != nil
}
/// 是否包含数字
var hasNumbers: Bool {
return rangeOfCharacter(from: .decimalDigits, options: .literal, range: nil) != nil
}
}
