How to convert a 4-bytes array into the corresponding Int?
let array: [UInt8] ==> let value : Int
Example:
\0\0\0\x0e
14
let data = NSData(bytes: array, length: 4)
data.getBytes(&size, length: 4)
// the output to size is 184549376
There are two problems:
Int
is a 64-bit integer on 64-bit platforms, your input data has only 32-bit.Int
uses a little-endian representation on all current Swift platforms, your input is big-endian.That being said the following would work:
let array : [UInt8] = [0, 0, 0, 0x0E]
var value : UInt32 = 0
let data = NSData(bytes: array, length: 4)
data.getBytes(&value, length: 4)
value = UInt32(bigEndian: value)
print(value) // 14
Or using Data
in Swift 3:
let array : [UInt8] = [0, 0, 0, 0x0E]
let data = Data(bytes: array)
let value = UInt32(bigEndian: data.withUnsafeBytes { $0.pointee })
With some buffer pointer magic you can avoid the intermediate copy to an NSData
object (Swift 2):
let array : [UInt8] = [0, 0, 0, 0x0E]
var value = array.withUnsafeBufferPointer({
UnsafePointer<UInt32>($0.baseAddress).memory
})
value = UInt32(bigEndian: value)
print(value) // 14
For a Swift 3 version of this approach, see ambientlight's answer.
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments