17

我正在尝试检查用户是否有互联网连接,并且该过程的一部分涉及调用withUnsafePointer. 在 Swift 1.x 中,我可以使用:

var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
zeroAddress.sin_family = sa_family_t(AF_INET)

let defaultRouteReachability = withUnsafePointer(&zeroAddress){
    SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0)).takeRetainedValue()
}

但是现在使用 Swift 2,我收到一条错误消息

无法使用类型为“(inout sockaddr_in,(_)-> _)”的参数列表调用“withUnsafePointer”

我查看了Xcode的用法,即:

在此处输入图像描述

所以我尝试使用

withUnsafePointer(&zeroAddress) {(pointer: UnsafePointer<sockaddr_in>) -> sockaddr_in in
    SCNetworkReachabilityCreateWithAddress(nil, pointer).takeRetainedValue()
}

withUnsafePointer(&zeroAddress) {(pointer: UnsafePointer<sockaddr_in>) -> AnyObject in
    SCNetworkReachabilityCreateWithAddress(nil, pointer).takeRetainedValue()
}

他们都给出了cannot invoke...编译时错误。withUnsafePointer在 Swift 2.x中使用的正确方法是什么?

4

3 回答 3

23

错误消息具有误导性,问题是 SCNetworkReachabilityCreateWithAddress()不再返回非托管对象,因此您不能调用 takeRetainedValue()

var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
zeroAddress.sin_family = sa_family_t(AF_INET)

let defaultRouteReachability = withUnsafePointer(&zeroAddress) {
    SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))
}

还要注意 C 结构的简化创建,如struct sockaddr_inSwift 1.2 引入的(如果我没记错的话)。

于 2015-06-09T18:34:21.363 回答
2

斯威夫特 3:

var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
zeroAddress.sin_family = sa_family_t(AF_INET)

let defaultRouteReachability = withUnsafePointer(to: &zeroAddress, {
    _ = $0.withMemoryRebound(to: sockaddr.self, capacity: 1) { zeroSockAddress in
        SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
    }
})
于 2016-09-20T11:04:04.983 回答
0

Swift3 使用这个

         var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
         zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
         zeroAddress.sin_family = sa_family_t(AF_INET)

         let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
            }
        }

        var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags(rawValue: 0)
        if SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) == false {
            return false
        }
于 2016-11-15T10:35:26.790 回答