Question

我使用Swift转换Keychain查询结果。

我的请求似乎有效：

let queryAttributes = NSDictionary(objects: [kSecClassGenericPassword, "MyService",     "MyAccount",       true],
                                   forKeys: [kSecClass,                kSecAttrService, kSecAttrAccount, kSecReturnData])


dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
    var dataTypeRef : Unmanaged<AnyObject>?
    let status = SecItemCopyMatching(queryAttributes, &dataTypeRef);

    let retrievedData : NSData = dataTypeRef!.takeRetainedValue() as NSData
    *** ^^^^can't compile this line^^^^
})

我的问题是，代码无法编译：

Bitcast requires both operands to be pointer or neither
  %114 = bitcast %objc_object* %113 to %PSs9AnyObject_, !dbg !487
Bitcast requires both operands to be pointer or neither
  %115 = bitcast %PSs9AnyObject_ %114 to i8*, !dbg !487
LLVM ERROR: Broken function found, compilation aborted!

我不知道如何将Unmanaged<AnyObject>转换为NSData。

有什么想法吗？

Answer 1

使用withUnsafeMutablePointer函数和UnsafeMutablePointer结构来检索数据，例如：

var result: AnyObject?
var status = withUnsafeMutablePointer(&result) { SecItemCopyMatching(queryAttributes, UnsafeMutablePointer($0)) }

if status == errSecSuccess {
    if let data = result as NSData? {
        if let string = NSString(data: data, encoding: NSUTF8StringEncoding) {
            // ...
        }
    }
}

它可以在发布（最快[-O]）构建时正常工作。

Answer 2

看起来你遇到了编辑错误，你应该报告。您可以采用不同的路径来检索值，例如：

    var dataTypeRef :Unmanaged<AnyObject>?
    let status = SecItemCopyMatching(queryAttributes, &dataTypeRef);

    let opaque = dataTypeRef?.toOpaque()

    if let op = opaque? {
        let retrievedData = Unmanaged<NSData>.fromOpaque(op).takeUnretainedValue()

    }

使用AnyObject作为T的类型参数Unmanaged<T>时，错误会自行显示。以下代码段编译没有问题，它使用更具体的类型CFError：

    let url = NSURL(string:"dummy")
    var errorRef: Unmanaged<CFError>?
    let succeeded = CTFontManagerRegisterFontsForURL(url, .Process, &errorRef)

    if errorRef {
        let error = errorRef!.takeRetainedValue()
    }

由于Keychain API根据查询属性返回不同的结果，因此需要使用AnyObject。

Answer 3

要使其正常工作，您需要首先访问每个钥匙串常量的保留值。例如：

let kSecClassValue = kSecClass.takeRetainedValue() as NSString
let kSecAttrAccountValue = kSecAttrAccount.takeRetainedValue() as NSString
let kSecValueDataValue = kSecValueData.takeRetainedValue() as NSString
let kSecClassGenericPasswordValue = kSecClassGenericPassword.takeRetainedValue() as NSString
let kSecAttrServiceValue = kSecAttrService.takeRetainedValue() as NSString
let kSecMatchLimitValue = kSecMatchLimit.takeRetainedValue() as NSString
let kSecReturnDataValue = kSecReturnData.takeRetainedValue() as NSString
let kSecMatchLimitOneValue = kSecMatchLimitOne.takeRetainedValue() as NSString

然后，您需要引用您在keychain字典对象中创建的常量，如此。

var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, userAccount, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])

我写了一篇关于它的博客文章：http://rshelby.com/2014/08/using-swift-to-save-and-query-ios-keychain-in-xcode-beta-4/

希望这有帮助！

rshelby

使用Swift查询iOS Keychain

3 个答案: