Question

我有一个Data类型的变量fileData，我很难找到如何打印它的大小。

在过去的NSData中，您可以打印长度但不能使用此类型。

如何在Swift 3.0中打印数据的大小？

Answer 1

使用yourData.count并除以1024 * 1024.使用Alexanders出色的建议：

    func stackOverflowAnswer() {
      if let data = UIImagePNGRepresentation(#imageLiteral(resourceName: "VanGogh.jpg")) as Data? {
      print("There were \(data.count) bytes")
      let bcf = ByteCountFormatter()
      bcf.allowedUnits = [.useMB] // optional: restricts the units to MB only
      bcf.countStyle = .file
      let string = bcf.string(fromByteCount: Int64(data.count))
      print("formatted result: \(string)")
      }
    }

得到以下结果：

There were 28865563 bytes
formatted result: 28.9 MB

Answer 2

如果您的目标是打印尺寸以使用，请使用ByteCountFormatter

import Foundation

let byteCount = 512_000 // replace with data.count
let bcf = ByteCountFormatter()
bcf.allowedUnits = [.useMB] // optional: restricts the units to MB only
bcf.countStyle = .file
let string = bcf.string(fromByteCount: Int64(byteCount))
print(string)

Answer 3

您可以使用count数据对象，但仍然可以将length用于NSData

Answer 4

Swift 5.1

extension Int {
    var byteSize: String {
        return ByteCountFormatter().string(fromByteCount: Int64(self))
    }
}

用法：

let yourData = Data()
print(yourData.count.byteSize)

Answer 5

在以下代码中输入文件URL，以MB为单位获取文件大小，希望对您有所帮助。

let data = NSData(contentsOf: FILE URL)!
let fileSize = Double(data.length / 1048576) //Convert in to MB
print("File size in MB: ", fileSize)

Answer 6

根据接受的答案，我创建了简单的扩展程序：

extension Data {
func sizeString(units: ByteCountFormatter.Units = [.useAll], countStyle: ByteCountFormatter.CountStyle = .file) -> String {
    let bcf = ByteCountFormatter()
    bcf.allowedUnits = units
    bcf.countStyle = .file

    return bcf.string(fromByteCount: Int64(count))
 }}

Answer 7

要获取字符串的大小，请改编自@mozahler's answer

if let data = "some string".data(using: .utf8)! {
  print("There were \(data.count) bytes")
  let bcf = ByteCountFormatter()
  bcf.allowedUnits = [.useKB] // optional: restricts the units to MB only
  bcf.countStyle = .file
  let string = bcf.string(fromByteCount: Int64(data.count))
  print("formatted result: \(string)")
}

Answer 8

用于将 Data 大小（以兆字节为单位）获取为 Double 的快速扩展。

extension Data {
    func getSizeInMB() -> Double {
        let bcf = ByteCountFormatter()
        bcf.allowedUnits = [.useMB]
        bcf.countStyle = .file
        let string = bcf.string(fromByteCount: Int64(self.count)).replacingOccurrences(of: ",", with: ".")
        if let double = Double(string.replacingOccurrences(of: " MB", with: "")) {
            return double
        }
        return 0.0
    }
}

Answer 9

count应该符合您的需求。您需要将字节转换为兆字节（Double(data.count) / pow(1024, 2)）

Answer 10

如果只想看字节数，直接打印数据对象可以为您提供。

let dataObject = Data()
print("Size is \(dataObject)")

应该给你：

Size is 0 bytes

换句话说，在较新的Swift 3.2或更高版本中，不需要.count。

在Swift 3.0中打印数据的大小（兆字节）

10 个答案: