Swift轉換：錯誤 - UnsafeMutablePointer

Question

我試圖將我的Swift 2代碼轉換成最新的語法（Swift 3）。我收到以下錯誤：

Cannot invoke initializer for type 'UnsafeMutablePointer<CUnsignedChar>' with an argument list of type '(UnsafeMutableRawPointer!)

斯威夫特2代碼：

let rawData = UnsafeMutablePointer<CUnsignedChar>(calloc(height * width * 4, Int(sizeof(CUnsignedChar)))) 

有人可以幫我解決這個轉換語法問題？

Answer 1

calloc返回一個「原始指針」（C中的Swift等效於void *）。 你可以用assumingMemoryBound其轉換爲一個類型的指針：

let rawData = calloc(width * height, MemoryLayout<CUnsignedChar>.stride).assumingMemoryBound(to: CUnsignedChar.self) 

或者使用UnsafeMutablePointer的allocate()方法：

let rawData = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: width * height) 
rawData.initialize(to: 0, count: width * height) 
// ... 

rawData.deinitialize() 
rawData.deallocate(capacity: width * height)