ios - 如何使用 Swift 1.2 传递来自 UnsafeMutablePointer 的输入

Question

在尝试了多种解决方法后，我陷入了困境。急切寻求帮助。

这是 playground 中的一个基本测试用例:

import JavaScriptCore

func NativeLoggingHook(context: JSContextRef, object: JSObjectRef,  thisObject: JSObjectRef, argumentCount: size_t, arguments: [JSValueRef],  inout exception: JSValueRef) -> JSValueRef {
    // Do something useful
    return JSValueMakeUndefined(context)
}

var JSObjectCallAsFunctionCallback: @objc_block (JSContextRef, JSObjectRef, JSObjectRef, size_t, UnsafePointer<JSValueRef>, UnsafeMutablePointer<JSValueRef>) -> JSValueRef = { context, object,  thisObject, argumentCount, arguments, exception -> JSValueRef in
    let buffer: [JSValueRef] = Array<JSValueRef>(UnsafeBufferPointer(start: arguments, count: argumentCount))
    return NativeLoggingHook(context, object,  thisObject, argumentCount, buffer, exception) // <- How do I pass the exception to my Swift function?
}

我假设我需要使用 Swift 1.2 将 UnsafePointer 转换为 UnsafeBufferPointer，但如何将 UnsafeMutablePointer 传递给接受输入输出的函数？我尝试了 & 和许多其他变体，但到目前为止没有运气。

更新:

这是我为处理桥接来自 Objective-C 和 Swift 的回调而采用的解决方案。

import JavaScriptCore

func NativeLoggingHook(context: JSContextRef, object: JSObjectRef,  thisObject: JSObjectRef, argumentCount: size_t, arguments: [JSValueRef], exception: UnsafePointer<JSValueRef>) -> JSValueRef {
    // Do something useful
    return JSValueMakeUndefined(context) }

let block: @objc_block (JSContextRef, JSObjectRef, JSObjectRef, size_t, UnsafePointer<JSValueRef>, UnsafeMutablePointer<JSValueRef>)
-> JSValueRef = { context, object,  thisObject, argumentCount, arguments, exception -> JSValueRef in
    let buffer: [JSValueRef] = Array<JSValueRef>(UnsafeBufferPointer(start: arguments, count: argumentCount))
    return NativeLoggingHook(context, object,  thisObject, argumentCount, buffer, &exception.memory) }

let imp : COpaquePointer =
    imp_implementationWithBlock(unsafeBitCast(block, AnyObject.self))

let callback : JSObjectCallAsFunctionCallback =
    unsafeBitCast(imp, JSObjectCallAsFunctionCallback.self)

func setNativeHook(hook: JSObjectCallAsFunctionCallback) -> Bool {
    // Do something useful
    return true }

println(setNativeHook(callback))

Answer 1

我不知道这是否真的适合你，但我通过解开指针包装器并通过引用传递结果来编译它:

import JavaScriptCore

func NativeLoggingHook(context: JSContextRef, object: JSObjectRef,  thisObject: JSObjectRef, argumentCount: size_t, arguments: [JSValueRef],  inout exception: JSValueRef) -> JSValueRef {
    // Do something useful
    return JSValueMakeUndefined(context)
}

var JSObjectCallAsFunctionCallback: @objc_block (JSContextRef, JSObjectRef, JSObjectRef, size_t, UnsafePointer<JSValueRef>, UnsafeMutablePointer<JSValueRef>) -> JSValueRef = {
    (context, object,  thisObject, argumentCount, arguments, exception) -> JSValueRef in

    let buffer: [JSValueRef] = Array<JSValueRef>(UnsafeBufferPointer(start: arguments, count: argumentCount))
    return NativeLoggingHook(context, object, thisObject, argumentCount, buffer, &exception.memory)
    // <- pass the underlying memory type by reference?
}