[英]How to convert a float value to byte array in swift?
我用于以字节为单位获取数据的代码,但我没有获取浮点值的正确字节数据
let count = data.length / sizeof(UInt32)
// create array of appropriate length:
var array = [UInt32](count: count, repeatedValue: 0)
// copy bytes into array
data.getBytes(&array, length:count * sizeof(UInt32))
print(array)
Float
到NSData
:
var float1 : Float = 40.0
let data = NSData(bytes: &float1, length: sizeofValue(float1))
print(data) // <00002042>
...然后回到Float
:
var float2 : Float = 0
data.getBytes(&float2, length: sizeofValue(float2))
print(float2) // 40.0
(同样适用于其他“简单”类型,如Double
, Int
,...)
更新 Swift 3,使用新的Data
类型:
var float1 : Float = 40.0
let data = Data(buffer: UnsafeBufferPointer(start: &float1, count: 1))
print(data as NSData) // <00002042>
let float2 = data.withUnsafeBytes { $0.pointee } as Float
print(float2) // 40.0
(另请参阅往返 Swift 数字类型到/来自 Data )
Swift 4及更高版本的更新:
var float1 : Float = 40.0
let data = Data(buffer: UnsafeBufferPointer(start: &float1, count: 1))
let float2 = data.withUnsafeBytes { $0.load(as: Float.self) }
print(float2) // 40.0
备注: load(as:)
要求数据正确对齐,对于Float
将在 4 字节边界上。 有关适用于任意对齐数据的其他解决方案,请参阅例如往返数据的往返 Swift 数字类型。
Swift 5解决方案
从Float
到[UInt8]
extension Float {
var bytes: [UInt8] {
withUnsafeBytes(of: self, Array.init)
}
}
用法:
let number: Float = 36.5
let bytes = number.bytes
从[UInt8]
到Float
bytes.withUnsafeBytes {
$0.load(fromByteOffset: 0, as: Float.self)
}
要转换为数据,只需将字节数组转换为Data
let data = Data(bytes)
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