我正在尝试检查用户是否具有互联网连接，部分过程涉及使用UnsafePointer调用。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))
zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
zeroAddress.sin_family = sa_family_t(AF_INET)
let defaultRouteReachability = withUnsafePointer(&zeroAddress){
SCNetworkReachabilityCreateWithAddress(nil,UnsafePointer($0)).takeRetainedValue()
}
但是现在用Swift 2，我得到一个错误的说法
Cannot invoke ‘withUnsafePointer’ with an argument list of type ‘(inout sockaddr_in,(_) -> _)’
我看了Xcode的用法，这是：
所以我试过使用
withUnsafePointer(&zeroAddress) {(pointer: UnsafePointer<sockaddr_in>) -> sockaddr_in in
SCNetworkReachabilityCreateWithAddress(nil,pointer).takeRetainedValue()
}
以及
withUnsafePointer(&zeroAddress) {(pointer: UnsafePointer<sockaddr_in>) -> AnyObject in
SCNetworkReachabilityCreateWithAddress(nil,pointer).takeRetainedValue()
}
错误信息是误导的，问题在于
SCNetworkReachabilityCreateWithAddress()不返回
不受管理的对象，所以你不能打电话
takeRetainedValue()：
SCNetworkReachabilityCreateWithAddress()不返回
不受管理的对象，所以你不能打电话
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，简化了C structs的创建，如struct sockaddr_in推出了Swift 1.2(如果我记得正确的话)。
