标签: cfdictionary

好吧,这是我在使用CGImageSource时遇到的情况,并注意到CFDictionary和NSDictionary之间的免费桥接在某些情况下似乎遇到了问题.我已设法构建以下示例以显示我的意思:

func optionalProblemDictionary() -> CFDictionary? {
    let key = "key"
    let value = "value"
    var keyCallBacks = CFDictionaryKeyCallBacks()
    var valueCallBacks = CFDictionaryValueCallBacks()

    let cfDictionary = CFDictionaryCreate(kCFAllocatorDefault, UnsafeMutablePointer(unsafeAddressOf(key)), UnsafeMutablePointer(unsafeAddressOf(value)), 1, &keyCallBacks, &valueCallBacks)
    return cfDictionary
}

相当简单(有点傻)但它的功能返回和可选的CFDictionary.尝试从此函数创建NSDictionary时,"fun"开始:

以下为什么不工作？

if let problemDictionary = optionalProblemDictionary() as? NSDictionary {
    print(problemDictionary) // never enters, no warnings, compiles just fine
}

虽然这很好吗？

if let cfDictionary = optionalProblemDictionary() {
    let problemDictionary = cfDictionary as NSDictionary
    print(problemDictionary)
}

XCode 7.0(7A220)

根据文档 CFDictionaryCreate用于实例化CFDictionary swift.

func CFDictionaryCreate(_ allocator: CFAllocator!,
                  _ keys: UnsafeMutablePointer<UnsafePointer<Void>>,
                  _ values: UnsafeMutablePointer<UnsafePointer<Void>>,
                  _ numValues: CFIndex,
                  _ keyCallBacks: UnsafePointer<CFDictionaryKeyCallBacks>,
                  _ valueCallBacks: UnsafePointer<CFDictionaryValueCallBacks>) -> CFDictionary!

我怎样才能创建keys和values参数？到目前为止,我已尝试使用swift的String类型,希望它会自动转换为适当的类型:

import Foundation

var keys : [String] = ["key1", "key2"]
var values : [String] = ["value1", "value2"]
var keyCallbacks = kCFTypeDictionaryKeyCallBacks
var valueCallbacks = kCFTypeDictionaryValueCallBacks
var dict : CFDictionary = CFDictionaryCreate(kCFAllocatorDefault,
    &keys, &values, 2, &keyCallbacks, &valueCallbacks)

不幸的是我收到一个错误,说String不是keys和values数组元素的正确类型:

main.swift:41:2: error: 'String' is …

将Swift 3中的Dictionary转换为CFDictionary的正确方法是什么？这样写是合法的吗？

 var dictionary:Dictionary<NSString, Int> = [:]

然后

 dictionary as CFDictionary

我正在将一些旧的Objective-C代码转换为Swift,所以我可以放弃一些不赞成使用的方法,但是我一直在崩溃,到目前为止我似乎无法弄清楚是什么导致了它.我从P12证书中获取私钥,这个方法似乎工作正常,直到我到达实际需要从CFArray获取字典的部分,即使数组中有值,应用程序也会崩溃.这是我的代码:

func privateKeyFromCertificate(p12Name: String, withPassword password: String) -> SecKeyRef {
    let resourcePath: String = NSBundle.mainBundle().pathForResource(p12Name, ofType: "p12")!
    let p12Data: NSData = NSData(contentsOfFile: resourcePath)!
    let key : NSString = kSecImportExportPassphrase as NSString
    let options : NSDictionary = [key : password]

    var privateKeyRef: SecKeyRef? = nil


    var items : CFArray?


    let securityError: OSStatus = SecPKCS12Import(p12Data, options, &items)

    let description : CFString = CFCopyDescription(items)
    print(description)

    if securityError == noErr && CFArrayGetCount(items) > 0 {
        let objects : CFDictionaryRef = CFArrayGetValueAtIndex(items, 0) as! CFDictionaryRef …

我想用 Swift 创建一些 PDF 页面。

这是我创建 PDF 页面的代码

// Initialize context and other stuff
CGPDFContextBeginPage(pdfContext, aDictionary);
CGContextDrawPDFPage(pdfContext, pdfPageRef)
CGPDFContextEndPage(pdfContext)

我对“aDictionary”变量有疑问。我想在 kCGPDFContextMediaBox 键下添加媒体框（CGRect 类型变量）值。该文档告诉我以下内容： The media box for the document or for a given page. This key is optional. If present, the value of this key must be a CFData object that contains a CGRect (stored by value, not by reference).

在 Objective-C 中，从 CGRect 创建 CFData 相当容易，但在 Swift 中我不知道如何创建它。这是我的 Objective-C 代码：

CGRect mediaBox = CGRectZero;
CFDataCreate(kCFAllocatorDefault, (const UInt8 *)&mediaBox, sizeof(mediaBox)); …