ios – 使用Swift的C API

我正在尝试跟踪网络状态.我浏览了 FXReachability的代码.具体是以下方法.

- (void)setHost:(NSString *)host
{
    if (host != _host)
    {
        if (_reachability)
        {
            SCNetworkReachabilityUnscheduleFromRunLoop(_reachability,CFRunLoopGetMain(),kcfRunLoopCommonModes);
            CFRelease(_reachability);
        }
        _host = [host copy];
        _status = FXReachabilityStatusUnkNown;
        _reachability = SCNetworkReachabilityCreateWithName(kcfAllocatorDefault,[_host UTF8String]);
        SCNetworkReachabilityContext context = { 0,( __bridge void *)self,NULL,NULL };
        SCNetworkReachabilitySetCallBACk(_reachability,ONEReachabilityCallBACk,&context);
        SCNetworkReachabilityscheduleWithRunLoop(_reachability,kcfRunLoopCommonModes);
    }
}

它的作用是不断检查与指定主机的连接.我正在尝试将此方法转换为Swift,我遇到了一些问题.

1.将主机字符串转换为UTF8.

我必须将主机字符串转换为UTF8并将其传递给SCNetworkReachabilityCreateWithName方法.我无法在Objective-C中找到Swift等效的UTF8String属性.但是String类型有一个名为utf8的属性.根据documentation,

如何获得字符串的完整UTF8表示而不是无符号8位(UInt8)值的集合？

2. SCNetworkReachabilitySetCallback的回调函数.

此函数的第二个参数需要某种类型的SCNetworkReachabilityCallBACk.我潜入了源文件,发现它实际上是一个类型.

typealias SCNetworkReachabilityCallBACk = CFunctionPointer<((SCNetworkReachability!,SCNetworkReachabilityFlags,UnsafeMutablePointer<Void>) -> Void)>

我这样定义了.

let reachabilityCallBACk: SCNetworkReachabilityCallBACk = {

}()

但是我得到了一个错误,在一个闭包中返回错误返回’SCNetworkReachabilityCallBACk’,当在该类型中你可以清楚地看到它返回Void.

这是错误的方法吗？

这些是我面临的问题.我已经在这几个小时了,没有运气,所以我真的很感激任何帮助.

谢谢.

let reachability = host.withCString {
    SCNetworkReachabilityCreateWithName(nil,$0).takeRetainedValue()
}

let reachability = SCNetworkReachabilityCreateWithName(nil,host).takeRetainedValue()

let host = "google.com"
var context = SCNetworkReachabilityContext(version: 0,info: nil,retain: nil,release: nil,copyDescription: nil)
let reachability = SCNetworkReachabilityCreateWithName(nil,host)!

SCNetworkReachabilitySetCallBACk(reachability,{ (_,flags,_) in
    print(flags)
},&context) 

SCNetworkReachabilityscheduleWithRunLoop(reachability,kcfRunLoopCommonModes)

let host = "google.com"
var context = SCNetworkReachabilityContext(version: 0,_) in
    print(flags)
    },&context)

SCNetworkReachabilityscheduleWithRunLoop(reachability,CFRunLoopMode.commonModes.rawvalue)