c回调接口里面，调用swift函数，编译提示报错

Question

下面的代码提示报错：A C function pointer cannot be formed from a local function that captures context

public typealias CP_OnNetPrinterDiscovered_Swift = (_ local_ip: String, _ discovered_mac: String, _ discovered_ip: String, _ discovered_name: String) -> Void;

public func CP_Port_EnumNetPrinter(timeout: Int, cancel: Bool, on_discovered: CP_OnNetPrinterDiscovered_Swift) {
    let timeout_c: UInt32 = UInt32(timeout)
    
    let cancel = UnsafeMutablePointer<Int32>.allocate(capacity: 0);
    cancel.initialize(to: 0);
    
    func on_discovered_c(local_ip: UnsafePointer<Int8>?, discovered_mac: UnsafePointer<Int8>?, discovered_ip: UnsafePointer<Int8>?, discovered_name: UnsafePointer<Int8>?, private_data: UnsafeRawPointer?) {
        on_discovered(String.init(cString: local_ip!), String.init(cString: discovered_mac!), String.init(cString: discovered_ip!), String.init(cString: discovered_name!))
    }
    
    //let private_data = Unmanaged<CP_OnNetPrinterDiscovered_Swift>.passUnretained(on_discovered).toOpaque()
    
    CP_Port_EnumNetPrinter(timeout_c, cancel, on_discovered_c, nil)
}

 

我描述一下问题：

1 CP_Port_EnumNetPrinter(timeout: Int, cancel: Bool, on_discovered: CP_OnNetPrinterDiscovered_Swift) 这个函数，内部会调用C语言函数CP_Port_EnumNetPrinter查找打印机

2 找到打印机之后，会触发回调函数on_discovered_c

3 我想在on_discovered_c中调用on_discovered函数，这样不行，会报错

 

因为现在有一个C语言写的库函数，他里面有个回调函数作为参数，而桥接文件生成的接口比较复杂，想转成swift能简单调用的格式，死活搞不定，有没有啥办法

Answer 1

用OC桥接一下