swift - 生成随机 Int64 + swift 3

Question

我们在下面的代码中收到警告。谁能指出哪里出了问题以及正确的方法是什么？

class func getRandomInt64() -> Int64 {
    var randomNumber: Int64 = 0
    withUnsafeMutablePointer(to: &randomNumber, { (randomNumberPointer) -> Void in
        let castedPointer = unsafeBitCast(randomNumberPointer, to: UnsafeMutablePointer<UInt8>.self)
         _ = SecRandomCopyBytes(kSecRandomDefault, 8, castedPointer)
    })
    return abs(randomNumber)
}

之前没问题，现在提示警告:

'unsafeBitCast' from 'UnsafeMutablePointer' to 'UnsafeMutablePointer' changes pointee type and may lead to undefined behavior; use the 'withMemoryRebound' method on 'UnsafeMutablePointer' to rebind the type of memory

Answer 1

Swift 3 引入了 withMemoryRebound，取代了 unsafeBitCast 和其他不安全的转换:https://developer.apple.com/reference/swift/unsafepointer/2430863-withmemoryrebound

在您的情况下正确使用它的方法:

class func getRandomInt64() -> Int64 {
    var randomNumber: Int64 = 0
    withUnsafeMutablePointer(to: &randomNumber, { (randomNumberPointer) -> Void in
        _ = randomNumberPointer.withMemoryRebound(to: UInt8.self, capacity: 8, { SecRandomCopyBytes(kSecRandomDefault, 8, $0) })
    })
    return abs(randomNumber)
}