Swift 3 - CFHostScheduleWithRunLoop crash

Question

我正在Swift中做反向DNS，我以前在Swift 2.2上的代码工作得很好，我也在Objective-C中实现了它。但是我不能使它在Swift 3.0中工作

2.2迅速

//: Let's set up the `sockaddr_in` C structure using the initializer.
var sin = sockaddr_in(
    sin_len: UInt8(sizeof(sockaddr_in)),
    sin_family: sa_family_t(AF_INET),
    sin_port: in_port_t(0),
    sin_addr: in_addr(s_addr: inet_addr(ip)),
    sin_zero: (0,0,0,0,0,0,0,0)
)
//: Now convert the structure into a `CFData` object.
let data = withUnsafePointer(&sin) { ptr in
    CFDataCreate(kCFAllocatorDefault, UnsafePointer(ptr), sizeof(sockaddr_in))
}
//: Create the `CFHostRef` with the `CFData` object and store the retained value for later use.
let host = CFHostCreateWithAddress(kCFAllocatorDefault, data).takeRetainedValue()
//: Now schedule the runloop for the host.
CFHostScheduleWithRunLoop(host!, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode)
var error = CFStreamError()
//: Start the info resolution.
CFHostStartInfoResolution(host!, .Names, &error)

3.0迅速

//: Let's set up the `sockaddr_in` C structure using the initializer.
var sin = sockaddr_in(
    sin_len: UInt8(sizeof(sockaddr_in)),
    sin_family: sa_family_t(AF_INET),
    sin_port: in_port_t(0),
    sin_addr: in_addr(s_addr: inet_addr(ip)),
    sin_zero: (0,0,0,0,0,0,0,0)
)
//: Now convert the structure into a `CFData` object.
let data = NSData(bytes: &sin, length: MemoryLayout<sockaddr_in>.size) as CFData
//: Create the `CFHostRef` with the `CFData` object and store the retained value for later use.
let host = CFHostCreateWithAddress(kCFAllocatorDefault, data).takeRetainedValue()
//: Now schedule the runloop for the host.
CFHostScheduleWithRunLoop(host!, CFRunLoopGetCurrent(), CFRunLoopMode.defaultMode as! CFString)
var error = CFStreamError()
//: Start the info resolution.
CFHostStartInfoResolution(host!, .Names, &error)

当我运行这段代码时，它会在

处崩溃

CFHostScheduleWithRunLoop

任何想法?

Answer 1

尝试替换:

CFRunLoopMode.defaultMode as! CFString

:

CFRunLoopMode.defaultMode!.rawValue