在Swift中使用SecRandomCopyBytes

问题描述

我想在Swift 3.0中使用SecRandomCopyBytes生成随机字节.这是我在Swift 2.2中做到的方式

I want to generate random bytes using SecRandomCopyBytes in Swift 3.0. Here is how I did it in Swift 2.2

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.如果我注释掉返回部分，它仍然显示Generic Parameter ResultType could not be inferred

In Swift 3, I tried to do it like this, since I know the concept of unsafemutablebytes is different now, but it doesn't allow me to return. If I comment out the return part, it still says 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
}

有人知道如何解决此问题吗?

Does anyone know how to fix this?

谢谢

推荐答案

您已关闭，但封闭中的return返回从闭包开始，而不是从外部函数开始.因此，在SecRandomCopyBytes()中仅应调用关闭，结果传回.

You were close, but return inside the closure returnsfrom the closure, not from the outer function.Therefore only SecRandomCopyBytes() should be called in theclosure, and the result passed back.

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"，可以推断出闭包类型自动，因此可以缩短为

For a "single-expression closure" the closure type can inferredautomatically, so this can be shortened to

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
    }
}

迅速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
    }
}

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