从调用雨燕C函数 [英] Calling C function from Swift

问题描述

我想打电话从斯威夫特C函数，但我不知道如何定义变量来传递参数。

函数C是：

  DBFGetFieldInfo（DBFHandle psDBF，诠释iField，字符* pszFieldName，为int * pnWidth，为int * pnDecimals）;
 

主要的问题是 pszFieldName ， pnWidth 和 pnDecimals INOUT参数。我试图做：

  VAR DBF：DBFHandle = DBFOpen（pszPath，RB）
VAR FNAME：[CCHAR] = []
VAR fieldWidth：的Int32 = 0
让fieldDecimals：的Int32 = 0让字段信息：DBFFieldType = DBFGetFieldInfo（DBF，我，FNAME，＆安培; fieldWidth，＆安培; fieldDecimals）
 

但它给我一个错误

 无法援引DBFGetFieldInfo与类型的参数列表（DBFHandle，的Int32 [CCHAR]，INOUT的Int32，INOUT的Int32）'
预计类型的参数列表（DBFHandle，的Int32，UnsafeMutablePointer＆LT; INT8＆gt;中UnsafeMutablePointer＆LT;的Int32＆gt;中UnsafeMutablePointer＆LT;＆的Int32 GT;）
 

任何想法？

解决方案

  UnsafeMutablePointer＆LT; INT8＆gt;中UnsafeMutablePointer＆LT;的Int32＆gt;中UnsafeMutablePointer＆LT;的Int32＆GT;
 

您需要将您的变量转换成该方法签名所需的适当类型。

C语法：

• const型*


• 键入*

斯威夫特语法：

• UnsafePointer


• UnsafeMutablePointer

这是苹果公司在其使用SWIFT与可可和Objective-C基准<一个覆盖href=\"https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithCAPIs.html\"相对=nofollow>设在这里。

I am trying to call a C function from Swift , but I do not know exactly how to define variables to pass parameters.

The function c is:

DBFGetFieldInfo( DBFHandle psDBF, int iField, char * pszFieldName, int * pnWidth, int * pnDecimals );

The main problem is pszFieldName, pnWidth and pnDecimals inout parameters. I tried made ​​:

var dbf:DBFHandle = DBFOpen(pszPath, "rb")
var fName:[CChar] = [] 
var fieldWidth:Int32 = 0
let fieldDecimals:Int32 = 0

let fieldInfo:DBFFieldType = DBFGetFieldInfo(dbf, i, fName, &fieldWidth, &fieldDecimals)

but it gives me an error

Cannot invoke 'DBFGetFieldInfo' with an argument list of type '(DBFHandle, Int32, [CChar], inout Int32, inout Int32)'
Expected an argument list of type '(DBFHandle, Int32, UnsafeMutablePointer<Int8>, UnsafeMutablePointer<Int32>, UnsafeMutablePointer<Int32>)'

Any ideas?

解决方案

UnsafeMutablePointer<Int8>, UnsafeMutablePointer<Int32>, UnsafeMutablePointer<Int32>

You need to convert your variables to the appropriate types required by the method signature.

C Syntax:

• const Type *
• Type *

Swift Syntax:

• UnsafePointer
• UnsafeMutablePointer

This is covered by Apple in their Using Swift with Cocoa and Objective-C reference located here.

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