NSAttributeString+extension

NSAttributeString+extension.swift

//
//  NSAttributeString+extension.swift
//  BMKP
//
//  Created by lyj on 13/03/2017.
//  Copyright © 2017 bmkp. All rights reserved.
//

import Foundation
import UIKit


extension NSTextAttachment {
    
    /// 便利构造方法，增加图片附件
    ///
    /// - Parameter image: 图片
    public convenience init(image: UIImage?) {
        self.init()
        self.image = image
    }
    
}


extension NSAttributedString {
    
    /// 基于 NSAttributedNames 的封装，请根据使用情况自行添加类型
    public enum Attribute {
        
        case font(UIFont)
        case foreground(UIColor)
        case background(UIColor)
        case paragraph(NSParagraphStyle)
        case attachment(NSTextAttachment)
        case underline(NSUnderlineStyle, UIColor?)
        case baselineOffset(Int)
        
        var value: [NSAttributedStringKey:Any] { return fill() }
        
        func fill(in result: [NSAttributedStringKey:Any] = [:]) -> [NSAttributedStringKey:Any] {
            var result = result
            switch self {
                
            case .font(let font):
                result[.font] = font
                
            case .foreground(let color):
                result[.foregroundColor] = color
                
            case .background(let color):
                result[.backgroundColor] = color
                
            case .paragraph(let style):
                result[.paragraphStyle] = style
                
            case .attachment(let attachment):
                result[.attachment] = attachment
                
            case .underline(let style, let color):
                result[.underlineStyle] = style.rawValue
                
                if let color = color {
                    result[.underlineColor] = color
                }
                
            case .baselineOffset(let value):
                result[.baselineOffset] = value
            }
            
            return result
        }
    }
    
    public var range: NSRange { return NSRange(location: 0, length: length) }
    
}

extension NSAttributedString {
    
    /// 便利构造函数
    ///
    /// - Parameters:
    ///   - string: 字符串
    ///   - attribute: 枚举属性
    public convenience init(string: String, attribute: Attribute) {
        self.init(string: string, attributes: [attribute])
    }
    
    /// 便利构造函数
    ///
    /// - Parameters:
    ///   - string: 字符串
    ///   - attributes: 枚举属性数组
    public convenience init(string: String, attributes: [Attribute]) {
        self.init(string: string, attributes: attributes.reduce([:], { $1.fill(in: $0 ?? [:]) }))
    }

}

extension NSMutableAttributedString {
    
    @discardableResult
    public func set(attribute: Attribute, range: NSRange? = nil) -> Self {
        addAttributes(attribute.value, range: range ?? self.range)
        return self
    }
    
    @discardableResult
    public func set(attributes: [Attribute], range: NSRange? = nil) -> Self {
        addAttributes(attributes.reduce([:], { $1.fill(in: $0) }), range: range ?? self.range)
        return self
    }
    
    /// 添加指定范围的字符串属性
    ///
    /// - Parameters:
    ///   - attribute: 枚举属性
    ///   - range: 范围
    /// - Returns: 对象本身，用于链式语法
    @discardableResult
    public func addAttribute(attribute: Attribute, range: NSRange? = nil) -> Self {
        addAttributes(attribute.value, range: range ?? self.range)
        return self
    }
    
    /// 添加指定范围的多个属性
    ///
    /// - Parameters:
    ///   - attributes: 枚举属性数组
    ///   - range: 范围
    /// - Returns: 对象本身，用于链式语法
    @discardableResult
    public func addAttributes(attributes: [Attribute], range: NSRange? = nil) -> Self {
        addAttributes(attributes.reduce([:], { $1.fill(in: $0) }), range: range ?? self.range)
        return self
    }
    
    /// 添加属性字符串到尾部
    ///
    /// - Parameter attrString: 属性字符串
    /// - Returns: 对象本身，用于链式语法
    @discardableResult
    public func append(attrString: NSAttributedString) -> Self {
        append(attrString)
        return self
    }
    
    /// 添加字符串到尾部，可以指定单个属性
    ///
    /// - Parameters:
    ///   - string: 字符串
    ///   - attribute: 枚举属性
    /// - Returns: 对象本身，用于链式语法
    @discardableResult
    public func append(string: String, attribute: Attribute) -> Self {
        return append(string: string, attributes: [attribute])
    }
    
    /// 添加字符串到尾部，可以指定多个属性
    ///
    /// - Parameters:
    ///   - string: 字符串
    ///   - attributes: 枚举属性数组
    /// - Returns: 对象本身，用于链式语法
    @discardableResult
    public func append(string: String, attributes: [Attribute] = []) -> Self {
        append(NSMutableAttributedString(string: string, attributes: attributes))
        return self
    }

}