在Swift中使用SecRandomCopyBytes

一尘不染

在Swift中使用SecRandomCopyBytes

swift

我想SecRandomCopyBytes在Swift 3.0中使用生成随机字节。这是我在Swift 2.2中所做的

private static func generateRandomBytes() -> String? {
    let data = NSMutableData(length: Int(32))

    let result = SecRandomCopyBytes(kSecRandomDefault, 32, UnsafeMutablePointer<UInt8>(data!.mutableBytes))
    if result == errSecSuccess {
        return data!.base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: 0))
    } else {
        print("Problem generating random bytes")
        return nil
    }
}

在Swift
3中，我尝试这样做，因为我知道unsafemutablebytes的概念现在有所不同，但是它不允许我返回。如果我评论退货部分，它仍然会说Generic Parameter ResultType could not be inferred

fileprivate static func generateRandomBytes() -> String? {
    var keyData = Data(count: 32)
    _ = keyData.withUnsafeMutableBytes {mutableBytes in
        let result = SecRandomCopyBytes(kSecRandomDefault, keyData.count, mutableBytes)
        if result == errSecSuccess {
            return keyData.base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: 0))
        } else {
            print("Problem generating random bytes")
            return nil
        }
    }
    return nil
}

有谁知道如何解决这一问题？

谢谢

阅读 332

2020-07-07

共1个答案

一尘不染

您已经关闭了，但是return内部的封闭是从封闭而不是外部函数返回的。因此，仅SecRandomCopyBytes()应在闭包中调用该方法，并将结果传递回去。

func generateRandomBytes() -> String? {

    var keyData = Data(count: 32)
    let result = keyData.withUnsafeMutableBytes {
        (mutableBytes: UnsafeMutablePointer<UInt8>) -> Int32 in
        SecRandomCopyBytes(kSecRandomDefault, 32, mutableBytes)
    }
    if result == errSecSuccess {
        return keyData.base64EncodedString()
    } else {
        print("Problem generating random bytes")
        return nil
    }
}

对于“单表达式闭包”，可以自动推断闭包类型，因此可以缩短为

func generateRandomBytes() -> String? {

    var keyData = Data(count: 32)
    let result = keyData.withUnsafeMutableBytes {
        SecRandomCopyBytes(kSecRandomDefault, 32, $0)
    }
    if result == errSecSuccess {
        return keyData.base64EncodedString()
    } else {
        print("Problem generating random bytes")
        return nil
    }
}

Swift 5更新：

func generateRandomBytes() -> String? {

    var keyData = Data(count: 32)
    let result = keyData.withUnsafeMutableBytes {
        SecRandomCopyBytes(kSecRandomDefault, 32, $0.baseAddress!)
    }
    if result == errSecSuccess {
        return keyData.base64EncodedString()
    } else {
        print("Problem generating random bytes")
        return nil
    }
}

2020-07-07