I have a ptr from a C library that points to an array of Floats. Its type is UnsafeMutablePointer. How do I create a native [Float] array from this in Swift 3?
Here's what I'm trying:
var reconstructedFloats = [Float](repeatElement(0, count: size))
reconstructedFloats.withUnsafeMutableBufferPointer {
let reconstructedFloatsPtr = $0
print(type(of:$0)) // "UnsafeMutableBufferPointer<Float>"
cFloatArrayPtr?.withMemoryRebound(to: [Float].self, capacity: size) {
UnsafeMutableRawPointer(reconstructedFloatsPtr.baseAddress!).storeBytes(of: $0.pointee, as: Float.self)
}
UnsafeMutableRawPointer(reconstructedFloatsPtr.baseAddress!).storeBytes(of: (cFloatArrayPtr?.pointee)!, as: Float.self)
}
That seems insanely overcomplicated so hopefully there's an easy way, but even this code produces a compile error: Type of expression is ambiguous without more context
.
If you want to plug it into a playground, here's a complete sample that contrives the cFloatArrayPtr:
// Let's contrive a C array ptr:
var size = 3
var someFloats: [Float] = [0.1, 0.2, 0.3]
var cFloatArrayPtr: UnsafeMutablePointer<Float>?
someFloats.withUnsafeMutableBufferPointer {
cFloatArrayPtr = $0.baseAddress
}
print(type(of:cFloatArrayPtr!)) // "UnsafeMutablePointer<Float>"
var reconstructedFloats = [Float](repeatElement(0, count: size))
reconstructedFloats.withUnsafeMutableBufferPointer {
let reconstructedFloatsPtr = $0
print(type(of:$0))
cFloatArrayPtr?.withMemoryRebound(to: [Float].self, capacity: size) {
UnsafeMutableRawPointer(reconstructedFloatsPtr.baseAddress!).storeBytes(of: $0.pointee, as: Float.self)
}
UnsafeMutableRawPointer(reconstructedFloatsPtr.baseAddress!).storeBytes(of: (cFloatArrayPtr?.pointee)!, as: Float.self)
}
print(reconstructedFloats)
You can make an UnsafeBufferPointer
from your pointer. UnsafeBufferPointer
is a Sequence
, so you can directly make an array from it:
let buffer = UnsafeBufferPointer(start: cFloatArrayPtr, count: size)
var reconstructedFloats = Array(buffer)
Of course, this creates a copy.
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