string - 如何将 UnsafePointer 转换为字符串？

Question

我试过这个方法:

String.stringWithCString(cString: UnsafePointer<CChar>, encoding: NSStringEncoding)

但不幸的是，它只适用于 UnsafePointer<CChar> .我不知道如何转换 UnsafePointer<CUnsignedChar>至 UnsafePointer<CChar> .

Answer 1

struct UnsafePointer<T>有一个构造函数，它接受一个不同的不安全指针输入参数:

/// Convert from a UnsafePointer of a different type.
///
/// This is a fundamentally unsafe conversion.
init<U>(_ from: UnsafePointer<U>)

因此您可以从 ptr : UnsafePointer<CUnsignedChar> 创建一个字符串与

let str = String.stringWithCString(UnsafePointer(ptr), encoding: someEncoding)

或者，在 UTF-8 编码的情况下，更简单地使用

let str = String.fromCString(UnsafePointer(ptr))

注意泛型类型 <CChar>是从这里的上下文自动推断出来的，即最后一行相当于

let str = String.fromCString(UnsafePointer<CChar>(ptr))