convert NSData Length from bytes to megs

Question

I am trying to NSLog the number of megs my NSData object is however currently all I can get is bytes by using

NSLog(@"%u", myData.length);

So how would I change this NSLog statement so I can see something like

2.00 megs

any help would be appreciated.

Answer 1

There are 1024 bytes in a kilobyte and 1024 kilobytes in a megabyte, so...

NSLog(@"File size is : %.2f MB",(float)myData.length/1024.0f/1024.0f);

Mind you, this is a simplistic approach that couldn't really properly accommodate for byte sizes below 1,048,576 bytes or above 1,073,741,823 bytes. For a more complete solution that can handle varying file sizes, see: ObjC/Cocoa class for converting size to human-readable string?

Or for OS X 10.8+ and iOS 6+

NSLog(@"%@", [[NSByteCountFormatter new] stringFromByteCount:data.length]);

In Swift:

print(ByteCountFormatter().string(fromByteCount: Int64(data.count)))

Answer 2

For Swift 3, in Mb:

let countBytes = ByteCountFormatter()
countBytes.allowedUnits = [.useMB]
countBytes.countStyle = .file
let fileSize = countBytes.string(fromByteCount: Int64(dataToMeasure!.count))

print("File size: \(fileSize)")

Answer 3

With Swift 5.1 and iOS 13, you can use one of the 5 following ways to solve your problem.

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#1. Using ByteCountFormatter's string(fromByteCount:countStyle:) class method

The following sample code shows how to implement string(fromByteCount:countStyle:) in order to print a file size by automatically converting bytes to a more appropriate storage unit (e.g. megabytes):

import Foundation

let url = Bundle.main.url(forResource: "image", withExtension: "png")!
let data = try! Data(contentsOf: url)

let byteCount = data.count
print(byteCount) // prints: 2636725

let displaySize = ByteCountFormatter.string(fromByteCount: Int64(byteCount), countStyle: .file)
print(displaySize) // prints: 2.6 MB

---

#2. Using ByteCountFormatter's string(fromByteCount:) method

The following sample code shows how to implement ByteCountFormatter's string(fromByteCount:) in order to print a file size by manually converting bytes to megabytes:

import Foundation

let url = Bundle.main.url(forResource: "image", withExtension: "png")!
let data = try! Data(contentsOf: url)

let byteCount = data.count
print(byteCount) // prints: 2636725

let formatter = ByteCountFormatter()
formatter.allowedUnits = [.useMB]
formatter.countStyle = .file
let displaySize = formatter.string(fromByteCount: Int64(byteCount))
print(displaySize) // prints: 2.6 MB

---

#3. Using ByteCountFormatter's string(from:countStyle:) class method and Measurement

The following sample code shows how to implement string(from:countStyle:) in order to print a file size by automatically converting bytes to a more appropriate storage unit (e.g. megabytes):

import Foundation

let url = Bundle.main.url(forResource: "image", withExtension: "png")!
let data = try! Data(contentsOf: url)

let byteCount = data.count
print(byteCount) // prints: 2636725

let byteSize = Measurement(value: Double(byteCount), unit: UnitInformationStorage.bytes)
let displaySize = ByteCountFormatter.string(from: byteSize, countStyle: .file)
print(displaySize) // prints: 2.6 MB

---

#4. Using ByteCountFormatter's string(from:) method and Measurement

The following sample code shows how to implement ByteCountFormatter's string(from:) and Measurement in order to print a file size by manually converting bytes to megabytes:

import Foundation

let url = Bundle.main.url(forResource: "image", withExtension: "png")!
let data = try! Data(contentsOf: url)

let byteCount = data.count
print(byteCount) // prints: 2636725

let byteSize = Measurement(value: Double(byteCount), unit: UnitInformationStorage.bytes)
let formatter = ByteCountFormatter()
formatter.allowedUnits = [.useMB]
formatter.countStyle = .file
let displaySize = formatter.string(from: byteSize)
print(displaySize) // prints: 2.6 MB

---

#5. Using MeasurementFormatter's string(from:) method and Measurement

The following sample code shows how to implement Measurement and MeasurementFormatter's string(from:) in order to print a file size by manually converting bytes to megabytes:

import Foundation

let url = Bundle.main.url(forResource: "image", withExtension: "png")!
let data = try! Data(contentsOf: url)

let byteCount = data.count
print(byteCount) // prints: 2636725

let byteSize = Measurement(value: Double(byteCount), unit: UnitInformationStorage.bytes)
let convertedSize = byteSize.converted(to: .megabytes)
let formatter = MeasurementFormatter()
let displaySize = formatter.string(from: convertedSize)
print(displaySize) // prints: 2.637 MB