Ios 将NSData长度从字节转换为兆字节

我正在尝试

NSLog

我的

NSData

对象的MEG数，但目前我只能使用

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

那么，我如何更改这个

NSLog

语句，以便看到类似的内容呢

2.00兆欧

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任何帮助都将不胜感激。

一个千字节中有1024个字节，一个兆字节中有1024个千字节，所以

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

请注意，这是一种过于简单的方法，无法真正适应1048576字节以下或1073741823字节以上的字节大小。有关可处理不同文件大小的更完整解决方案，请参阅：

或适用于OS X 10.8+和iOS 6+

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

迅速：

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

对于Swift 3，单位为Mb：

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

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

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使用Swift 5.1和iOS 13，您可以使用以下5种方法之一来解决问题

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#1.使用字节计数格式化程序的类方法 以下示例代码显示了如何实现

字符串（fromByteCount:countStyle:）

，以便通过自动将字节转换为更合适的存储单元（例如兆字节）来打印文件大小：

---

#2.使用字节计数格式化程序的方法 以下示例代码显示了如何实现

字节计数格式化程序
的
字符串（fromByteCount:）
，以便通过手动将字节转换为兆字节来打印文件大小：

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

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

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

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

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


#3.使用
字节计数格式化程序
的类方法和
度量
以下示例代码显示了如何实现
字符串（from:countStyle:）
，以便通过自动将字节转换为更合适的存储单元（例如兆字节）来打印文件大小：


#4.使用字节计数格式化程序的方法和测量
以下示例代码显示了如何实现
字节计数格式化程序
的
字符串（from:）
和
测量
，以便通过手动将字节转换为兆字节来打印文件大小：

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

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

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

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

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


#5.使用
MeasurementFormatter
的方法和
Measurement
以下示例代码显示了如何实现
测量
和
测量格式
的
字符串（从：）
，以便通过手动将字节转换为兆字节来打印文件大小：

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

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

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

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

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

我该如何格式化它，使它后面有两个小数位。很酷，谢谢你的帮助。。我觉得我必须要有括号等等，这让我很困惑，但这很好地工作了！：）如果需要向用户显示，则不要使用字符串格式。相反，请使用NSNumberFormatter。这将为用户的locale.quick和hand设置格式。如何在没有MB的情况下将mega中的大小作为一个双倍值来获取很有帮助？@user1553381您可以将
ByteCountFormatter
的属性设置为
false
，以便只包含计数。