Helper for calculating String and NSAttributedString frame

AZTextFrame.swift

import UIKit

class AZTextFrameAttributes: NSObject {
  
  // MARK: - Properties
  
  fileprivate(set) var width: CGFloat = 0
  fileprivate(set) var string: String?
  fileprivate(set) var attributedString: NSAttributedString?
  
  // MARK: - Attributes
  
  var attributes: [String: AnyObject] = [:]
  var lineBreakingMode: NSLineBreakMode = NSLineBreakMode.byWordWrapping {
    didSet {
      let paragraph = NSMutableParagraphStyle()
      paragraph.lineBreakMode = lineBreakingMode
      attributes[NSParagraphStyleAttributeName] = paragraph
    }
  }
  
  // MARK: - Init
  
  init(string: String, font: UIFont) {
    self.string = string
    self.attributes = [NSFontAttributeName: font]
  }
  
  init(string: String, width: CGFloat, font: UIFont) {
    self.string = string
    self.width = width
    self.attributes = [NSFontAttributeName: font]
  }
  
  init(attributedString: NSAttributedString) {
    self.attributedString = attributedString
  }
  
  init(attributedString: NSAttributedString, width: CGFloat) {
    self.attributedString = attributedString
    self.width = width
  }
  
  // MARK: - Calculation
  
  func calculatedTextWidth() -> CGFloat {
    return AZTextFrame(attributes: self).width
  }
  
  func calculatedTextHeight() -> CGFloat {
    return AZTextFrame(attributes: self).height
  }
}

class AZTextFrame: NSObject {
  
  // MARK: - Properties
  
  let attributes: AZTextFrameAttributes
  fileprivate(set) var width: CGFloat = 0
  fileprivate(set) var height: CGFloat = 0
  
  // MARK: - Init
  
  init(attributes: AZTextFrameAttributes) {
    self.attributes = attributes
    super.init()
    self.calculate()
  }
  
  private func calculate() {
    let sizeForHeight = CGSize(width: attributes.width, height: CGFloat.greatestFiniteMagnitude / 2)
    let sizeForWidth = CGSize(width: CGFloat.greatestFiniteMagnitude / 2, height: CGFloat.greatestFiniteMagnitude / 2)
    
    if let string = attributes.string {
      height = (string as NSString).boundingRect(with: sizeForHeight, options: .usesLineFragmentOrigin, attributes: attributes.attributes, context: nil).height
      width = (string as NSString).boundingRect(with: sizeForWidth, options: .usesLineFragmentOrigin, attributes: attributes.attributes, context: nil).width
    } else if let attributedString = attributes.attributedString {
      height = attributedString.boundingRect(with: sizeForHeight, options: .usesLineFragmentOrigin, context: nil).height
      width = attributedString.boundingRect(with: sizeForWidth, options: .usesLineFragmentOrigin, context: nil).width
    }
    
    height = roundTillHalf(value: height)
    width = roundTillHalf(value: width)
  }
  
  private func roundTillHalf(value: CGFloat) -> CGFloat {
    if value - CGFloat(Int(value)) >= 0.5 {
      return CGFloat(Int(value)) + 1
    } else {
      return CGFloat(Int(value)) + 0.5
    }
  }
}