UIViewController subclass to show both the Settings app displayed free space, and the real free space.

FreeSpaceViewController.swift

//
//  FreeSpaceViewController.swift
//  Free Space
//
//  Created by Kyle Howells on 04/05/2022.
//

import UIKit

class FreeSpaceViewController: UIViewController {
	
	let byteFormatter:ByteCountFormatter = {
		let formatter = ByteCountFormatter()
		formatter.allowedUnits = .useAll
		formatter.countStyle = .file
		formatter.includesUnit = true
		formatter.isAdaptive = true
		return formatter
	}()
	
	private let textView:UITextView = {
		let textView = UITextView()
		textView.backgroundColor = UIColor.white
		textView.textColor = UIColor.black
		textView.font = UIFont.systemFont(ofSize: 14, weight: .medium)
		textView.isEditable = false
		textView.contentInsetAdjustmentBehavior = .never
		return textView
	}()
	
	
	
	// MARK: - View Setup

	let settingsTitleLabel:UILabel = {
		let l = UILabel()
		l.font = UIFont.systemFont(ofSize: 16, weight: .medium)
		l.text = "Settings App (Important Files)"
		return l
	}()
	let settingsStorageBar:KHFileStorageView = KHFileStorageView()
	
	let realTitleLabel:UILabel = {
		let l = UILabel()
		l.font = UIFont.systemFont(ofSize: 16, weight: .medium)
		l.text = "Real Storage Usage"
		return l
	}()
	let realStorageBar:KHFileStorageView = KHFileStorageView()
	
	
	override func viewDidLoad() {
		super.viewDidLoad()
		// Do any additional setup after loading the view.
		
		
		// formatter.string(fromByteCount: 123456789000) // '123.46 GB'
		// formatter.string(fromByteCount: 0) // 'Zero KB'
		// self.byteFormatter
		
		self.view.addSubview(self.textView)
		
		self.view.addSubview(self.settingsStorageBar)
		self.view.addSubview(self.settingsTitleLabel)
		
		self.view.addSubview(self.realStorageBar)
		self.view.addSubview(self.realTitleLabel)
		
		
		
		var text = "\n"
		
		text += "Total Space: \( self.byteFormatter.string(fromByteCount: Int64(getTotalSpace() ?? 0))) \n"
		text += "Total Real Free Space: \( self.byteFormatter.string(fromByteCount: Int64(getRealFreeSpace() ?? 0))) \n"
		text += "Total Important Free Space: \( self.byteFormatter.string(fromByteCount: getImportantFreeSpace() ?? 0)) \n"
		text += "Total Opportunistic Free Space: \( self.byteFormatter.string(fromByteCount: getOpportunisticFreeSpace() ?? 0)) \n"
		
		self.textView.text = text
		
		
		
		guard let _totalSpace = getTotalSpace() else { return }
		guard let _freeSpace = getRealFreeSpace() else { return }
		guard let importantFreeSpace = getImportantFreeSpace() else { return }
		//guard let opportunisticFreeSpace = getOpportunisticFreeSpace() else { return }
		
		let totalSpace = Int64(_totalSpace)
		let freeSpace = Int64(_freeSpace)
		
		self.settingsStorageBar.totalSpace = totalSpace
		self.settingsStorageBar.usedSpace = (totalSpace - importantFreeSpace)
		
		self.realStorageBar.totalSpace = totalSpace
		self.realStorageBar.usedSpace = (totalSpace - freeSpace)
	}
	
	
	// MARK: - Layout
	
	override func viewDidLayoutSubviews() {
		super.viewDidLayoutSubviews()
		let size = self.view.bounds.size
		//let safeArea = self.view.safeAreaInsets
		
		let width = size.width * 0.9
		
		// - Settings
		
		self.settingsTitleLabel.frame = {
			var frame = CGRect()
			frame.size.height = self.settingsTitleLabel.intrinsicContentSize.height
			frame.size.width = width
			frame.origin.x = (size.width - frame.width) * 0.5
			frame.origin.y = (size.height * 0.3)
			return frame
		}()
		
		self.settingsStorageBar.frame = {
			var frame = CGRect()
			frame.size.height = self.settingsStorageBar.intrinsicContentSize.height
			frame.size.width = width
			frame.origin.x = (size.width - frame.width) * 0.5
			frame.origin.y = self.settingsTitleLabel.frame.maxY + 10
			return frame
		}()
		
		
		// - Real
		
		self.realTitleLabel.frame = {
			var frame = CGRect()
			frame.size.height = self.settingsTitleLabel.intrinsicContentSize.height
			frame.size.width = width
			frame.origin.x = (size.width - frame.width) * 0.5
			frame.origin.y = self.settingsStorageBar.frame.maxY + 40
			return frame
		}()
		
		self.realStorageBar.frame = {
			var frame = CGRect()
			frame.size.width = width
			frame.size.height = self.realStorageBar.intrinsicContentSize.height
			frame.origin.x = (size.width - frame.width) * 0.5
			frame.origin.y = self.realTitleLabel.frame.maxY + 10
			return frame
		}()
		
		
		self.textView.frame = {
			var frame = CGRect()
			frame.origin.y = self.realStorageBar.frame.maxY + 30
			frame.size.height = size.height - frame.origin.y
			
			frame.size.width = width
			frame.origin.x = (size.width - frame.width) * 0.5
			return frame
		}()
		
	}
	
}




// MARK: - Get Free Space


func getTotalSpace() -> Int? {
	let fileURL = URL(fileURLWithPath: NSHomeDirectory() as String)
	do {
		let values = try fileURL.resourceValues(forKeys: [.volumeTotalCapacityKey])
		if let capacity = values.volumeTotalCapacity {
			print("Total capacity: \(capacity)")
			return capacity
		} else {
			print("Capacity is unavailable")
		}
	} catch {
		print("Error retrieving capacity: \(error.localizedDescription)")
	}
	
	return nil
}


func getRealFreeSpace() -> Int? {
	let fileURL = URL(fileURLWithPath: NSHomeDirectory() as String)
	do {
		let values = try fileURL.resourceValues(forKeys: [.volumeAvailableCapacityKey])
		if let capacity = values.volumeAvailableCapacity {
			print("Available capacity: \(capacity)")
			return capacity
		} else {
			print("Capacity is unavailable")
		}
	} catch {
		print("Error retrieving capacity: \(error.localizedDescription)")
	}
	
	return nil
}


func getImportantFreeSpace() -> Int64? {
	let fileURL = URL(fileURLWithPath: NSHomeDirectory() as String)
	do {
		let values = try fileURL.resourceValues(forKeys: [.volumeAvailableCapacityForImportantUsageKey])
		if let capacity: Int64 = values.volumeAvailableCapacityForImportantUsage {
			print("Available capacity for important usage: \(capacity)")
			return capacity
		} else {
			print("Capacity is unavailable")
		}
	} catch {
		print("Error retrieving capacity: \(error.localizedDescription)")
	}
	
	return nil
}


func getOpportunisticFreeSpace() -> Int64? {
	let fileURL = URL(fileURLWithPath: NSHomeDirectory() as String)
	do {
		let values = try fileURL.resourceValues(forKeys: [.volumeAvailableCapacityForOpportunisticUsageKey])
		if let capacity: Int64 = values.volumeAvailableCapacityForOpportunisticUsage {
			print("Available capacity for important usage: \(capacity)")
			return capacity
		} else {
			print("Capacity is unavailable")
		}
	} catch {
		print("Error retrieving capacity: \(error.localizedDescription)")
	}
	
	return nil
}

KHFileStorageView.swift

//
//  KHFileStorageView.swift
//  Free Space
//
//  Created by Kyle Howells on 05/05/2022.
//

import Foundation
import UIKit

class KHFileStorageView: UIView {
	
	// MARK: - Properties
	
	var totalSpace:Int64 = 100 {
		didSet {
			self.update()
		}
	}
	var usedSpace:Int64 = 50 {
		didSet {
			self.update()
		}
	}
	
	
	let byteFormatter:ByteCountFormatter = {
		let formatter = ByteCountFormatter()
		formatter.allowedUnits = .useAll
		formatter.countStyle = .file
		formatter.includesUnit = true
		formatter.isAdaptive = true
		return formatter
	}()
	
	
	// MARK: - Views
	
	let usedBackgroundView:UIView = {
		let view = UIView()
		view.backgroundColor = UIColor(red: 44.0/255.0, green: 67.0/255.0, blue: 136.0/255.0, alpha: 1.0)
		return view
	}()
	
	let usedSpaceLabel:UILabel = {
		let l = UILabel()
		l.textColor = UIColor(red: 44.0/255.0, green: 67.0/255.0, blue: 136.0/255.0, alpha: 1.0)
		l.font = UIFont.systemFont(ofSize: 13, weight: .medium)
		return l
	}()
	
	
	let freeBackgroundView:UIView = {
		let view = UIView()
		view.backgroundColor = UIColor(red: 206.0/255.0, green: 206.0/255.0, blue: 207.0/255.0, alpha: 1.0)
		return view
	}()
	
	let freeSpaceLabel:UILabel = {
		let l = UILabel()
		l.textColor = UIColor(red: 206.0/255.0, green: 206.0/255.0, blue: 207.0/255.0, alpha: 1.0)
		l.font = UIFont.systemFont(ofSize: 13, weight: .medium)
		return l
	}()
	
	
	// MARK: - Setup
	
	override init(frame: CGRect) {
		super.init(frame: frame)
		self.commonInit()
	}
	
	required init?(coder: NSCoder) {
		super.init(coder: coder)
		self.commonInit()
	}
	
	func commonInit() {
		self.addSubview(self.freeSpaceLabel)
		self.addSubview(self.freeBackgroundView)
		
		self.addSubview(self.usedSpaceLabel)
		self.addSubview(self.usedBackgroundView)
	}
	
	
	private func update() {
		let usedSpaceString = self.byteFormatter.string(fromByteCount: self.usedSpace)
		self.usedSpaceLabel.text = "Used: \(usedSpaceString)"
		
		let freeSpaceString = self.byteFormatter.string(fromByteCount: self.totalSpace - self.usedSpace)
		self.freeSpaceLabel.text = "Free: \(freeSpaceString)"
		
		self.setNeedsLayout()
	}
	
	
	// MARK: - Size
	
	private let barHeight:CGFloat = 30
	
	override func sizeThatFits(_ size: CGSize) -> CGSize {
		return CGSize(width: size.width, height: self.barHeight + self.freeSpaceLabel.font.lineHeight)
	}
	
	override var intrinsicContentSize: CGSize {
		return CGSize(
			width: 320,
			height: self.barHeight + self.freeSpaceLabel.font.lineHeight
		)
	}
	
	
	// MARK: - Layout
	
	override func layoutSubviews() {
		super.layoutSubviews()
		let size = self.bounds.size
		
		let usedPercent = CGFloat(self.usedSpace) / CGFloat(self.totalSpace)
		let usedSpaceWidth = size.width * usedPercent
		
		self.usedBackgroundView.frame = {
			var frame = CGRect()
			frame.size.width = usedSpaceWidth
			frame.size.height = self.barHeight
			frame.origin.x = 0
			frame.origin.y = 0
			return frame
		}()
		
		self.usedSpaceLabel.frame = {
			var frame = CGRect()
			frame.size = self.usedSpaceLabel.intrinsicContentSize
			
			frame.origin.x = 0
			frame.origin.y = self.usedBackgroundView.frame.maxY
			return frame
		}()
		
		
		let freePercent = CGFloat(self.totalSpace - self.usedSpace) / CGFloat(self.totalSpace)
		let freeSpaceWidth = size.width * freePercent
		
		self.freeBackgroundView.frame = {
			var frame = CGRect()
			frame.size.width = freeSpaceWidth
			frame.size.height = self.barHeight
			frame.origin.x = size.width - frame.width
			frame.origin.y = 0
			return frame
		}()
		
		self.freeSpaceLabel.frame = {
			var frame = CGRect()
			frame.size = self.freeSpaceLabel.intrinsicContentSize
			
			frame.origin.x = size.width - frame.width
			frame.origin.y = self.freeBackgroundView.frame.maxY
			return frame
		}()
		
	}
	
}