如何传递UnsafeMutablePointertypes的参数<UnsafePointer <Void >>

我必须在Swift中使用CFDictionaryCreate方法（ 文档链接 ）。

我很难正确初始化input参数，以传递UnsafeMutablePointer<UnsafePointer<Void>>types的参数（键和值）。

这是我的代码：

  var font_name: CFStringRef! = CFStringCreateWithCString(nil, "Courier", kCFStringEncodingASCII) var font: CTFontRef! = CTFontCreateWithName(font_name, 25.0, nil) var keys: [UnsafePointer<Void>] = ???? // how to intialize with "kCTFontAttributeName" var values: [UnsafePointer<Void>] = ???? // how to intialize with "font" variable var keyCallBacks = kCFTypeDictionaryKeyCallBacks var valueCallBacks = kCFTypeDictionaryValueCallBacks var font_attributes: CFDictionaryRef! = CFDictionaryCreate(kCFAllocatorDefault, &keys, &values, sizeofValue(keys), &keyCallBacks, &valueCallBacks) var attr_string: CFAttributedStringRef! = CFAttributedStringCreate(nil, "hello", font_attributes) 

Answer 1

你可以简单地使用一个types为[ NSString : AnyObject ]的Swift字典，它会自动桥接到NSDictionary或CFDictionary 。 请注意，你也不需要CFStringRef 。

 let font = CTFontCreateWithName("Courier", 25.0, nil) let attributes : [ NSString : AnyObject ] = [ kCTFontAttributeName : font ] let attrString = CFAttributedStringCreate(nil, "Hello", attributes) 

或者，

 let attrString = NSAttributedString(string: "Hello", attributes: attributes) 

因为NSAttributedString是用CFAttributedString桥接免费的。

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只是为了完整性，这里是如何使用CFDictionaryCreate() ：

 let font = CTFontCreateWithName("Courier", 25.0, nil) var keys = [ unsafeAddressOf(kCTFontAttributeName) ] var values = [ unsafeAddressOf(font) ] var keyCallbacks = kCFTypeDictionaryKeyCallBacks var valueCallbacks = kCFTypeDictionaryValueCallBacks let attributes = CFDictionaryCreate(nil, &keys, &values, 1, &keyCallbacks, &valueCallbacks) let attrString = CFAttributedStringCreate(nil, "Hello", attributes)