Swift：将数据传递到捕获上下文的闭包

Swift：将数据传递到捕获上下文的闭包

类似于如何将实例方法用作仅使用func或立即数闭包的函数的回调中一样，您必须转换

self

为void指针，将其存储在上下文中，然后将其转换回闭包中的对象指针：

func checkForConnection() {    let host = "reddit.com"    var context = SCNetworkReachabilityContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)    context.info = UnsafeMutablePointer(Unmanaged.passUnretained(self).toOpaque())    let reachability = SCNetworkReachabilityCreateWithName(nil, host)!    SCNetworkReachabilitySetCallback(reachability, { (_, flags, info) in        if flags.rawValue == 0 { //internet is not connected        } else { //internet became connected let mySelf = Unmanaged<ViewController>.fromOpaque(COpaquePointer(info)).takeUnretainedValue() if mySelf.updateonConnection {     mySelf.refreshWallpaper() }        }        }, &context)    SCNetworkReachabilityScheduleWithRunLoop(reachability, CFRunLoopGetMain(), kCFRunLoopCommonModes)}

备注：

if flags.rawValue == 0

可以表示得稍微优雅一些

if flags.isEmpty

，但是您 实际上
应该检查的是

if flags.contains(.Reachable)

。

---

Swift 3的更新（Xpre 8 beta 6）：

func checkForConnection() {    let host = "reddit.com"    var context = SCNetworkReachabilityContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)    context.info = UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque())    let reachability = SCNetworkReachabilityCreateWithName(nil, host)!    SCNetworkReachabilitySetCallback(reachability, { (_, flags, info) in        if let info = info { if flags.rawValue == 0 { //internet is not connected } else { //internet became connected     let mySelf = Unmanaged<ViewController>.fromOpaque(info).takeUnretainedValue()     // ... }        }    }, &context)    SCNetworkReachabilityScheduleWithRunLoop(reachability, CFRunLoopGetMain(), CFRunLoopMode.commonModes.rawValue)}