在Swift的SQLite项目中发布UnsafePointer

We are implementing SQLite in iOS, in Swift, without using wrappers or Objective-C bridging. Everything works fine, except when doing a query and extracting the result. The issue is with the UnsafePointer<UInt8> that is returned from SQLite in Swift as follows:

我们在iOS和Swift中实现了SQLite，而不使用包装器或Objective-C桥接。除了在执行查询和提取结果时之外，一切都运行良好。该问题是与UnsafePointer ，由SQLite以Swift方式返回:

var querySQL = "SELECT address, phone FROM CONTACTS WHERE NAME = 'myName'"
var cQuery = querySQL.cStringUsingEncoding(NSUTF8StringEncoding)
var statement: COpaquePointer = nil
if sqlite3_prepare_v2(contactsDB, cQuery!, -1, &statement, nil) == SQLITE_OK {
   if sqlite3_step(statement) == SQLITE_ROW {
   var address : UnsafePointer<UInt8> = sqlite3_column_text(statement, 0)
   var data = NSData(bytes: address, length: 10)
   var string = NSString(data: data, encoding: NSUTF8StringEncoding)
   println(string)

As you can see, we can convert the pointer to String if we know the length of the object (in this case 10)

如您所见，如果我们知道对象的长度，我们可以将指针转换为String(在本例中为10)

To dig into this issue, I have the following example

要深入研究这个问题，我有以下示例

let pointerFromString: UnsafePointer<Int8> = "xyz".cStringUsingEncoding(NSUTF8StringEncoding)
let stringFromPointer = String.fromCString(anotherPointerFromString_Int8)                    println(stringFromPointer!)

Given that CChar is an alias of Int8, I can convert a String to UnsafePointer<Int8> using .cStringUsingEncoding(), and then back to String using .fromCString(<UnsafePointer_CChar>)

假设CChar是Int8的别名，我可以使用.cStringUsingEncoding()将一个字符串转换为UnsafePointer ，然后使用.fromCString( )返回到字符串

The problem is that my SQLite result is a UnsafePointer_UInt8, that can´t be used with .fromCString()

问题是我的SQLite结果是UnsafePointer_UInt8,´t可以使用.fromCString()

The bottom line question is: Is it possible to convert or cast a UnsafePointer_UInt8 to UnsafePointer_Int8

底线问题是:是否可能将UnsafePointer_UInt8转换或转换为UnsafePointer_Int8

1 个解决方案

#1

This should work:

这应该工作:

let address = sqlite3_column_text(statement, 0)
let string = String.fromCString(UnsafePointer<CChar>(address))

Update for Swift 3 (Xcode 8), compare Swift 3: convert a null-terminated UnsafePointer<UInt8> to a string:

更新Swift 3 (Xcode 8)，比较Swift 3:将空终止的UnsafePointer 转换为字符串:

let string = String(cString: sqlite3_column_text(statement, 0))

#1