在Swift中如何将CFStringRef []和CFTypeRef []转换为CMutablePointer＆lt; COpaquePointer＆gt;？

Question

在Swift中如何将CFStringRef[]和CFTypeRef[]转换为CMutablePointer< COpaquePointer >？

我想从Swift致电CFDictionaryCreate。我已定义：

var keys: CFStringRef[] = [kCGImageSourceCreateThumbnailWithTransform, kCGImageSourceCreateThumbnailFromImageIfAbsent, kCGImageSourceThumbnailMaxPixelSize, kCGImageSourceCreateThumbnailFromImageAlways]

var values: CFTypeRef[] = [kCFBooleanTrue, kCFBooleanTrue, imageSize, kCFBooleanTrue]

CFDictionaryCreate(nil, keys, values, 4, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks)

但不知道如何在上述调用中指定键和值。

Answer 1

我可以通过为你创建不安全的指针来让编译器停止抱怨，但是我对其余的CFDictionary用法不太了解。

import ImageIO

let dictionayKeyCB = UnsafePointer<CFDictionaryKeyCallBacks>()
let valueKeyCB = UnsafePointer<CFDictionaryValueCallBacks>()

let keys: [CFStringRef] = [kCGImageSourceCreateThumbnailWithTransform, kCGImageSourceCreateThumbnailFromImageIfAbsent, kCGImageSourceThumbnailMaxPixelSize, kCGImageSourceCreateThumbnailFromImageAlways]
let keysPointer =  UnsafeMutablePointer<UnsafePointer<Void>>.alloc(1)
keysPointer.initialize(keys)

let values: [CFTypeRef] = [kCFBooleanTrue, kCFBooleanTrue, kCFBooleanTrue, kCFBooleanTrue]
let valuesPointer =  UnsafeMutablePointer<UnsafePointer<Void>>.alloc(1)
valuesPointer.initialize(values)

CFDictionaryCreate(kCFAllocatorDefault, keysPointer, valuesPointer, 4, dictionayKeyCB, valueKeyCB)