Swift与C char*

最新推荐文章于 2021-05-20 16:46:38 发布

vickyjfr

最新推荐文章于 2021-05-20 16:46:38 发布

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本文探讨了Swift中使用UnsafePointer进行内存管理的方法，包括如何安全地与C指针交互，以及通过UnsafePointer来传递数据到函数的具体实现细节。

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myFunc(u8* data, u8 lengthOfData); //(NOTE: u8 is defined as unsigned char)

var someData = SomeStruct(someValue: 1)
withUnsafeMutablePointer(&someData) {
    myFunc(UnsafeMutablePointer($0), UInt8(sizeof(SomeStruct)))
}
myFunc(const u8* data, u8 lengthOfData);
withUnsafePointer(&someData) {
    myFunc(UnsafePointer($0), UInt8(sizeof(SomeStruct)))
}

let commandsToPrint: NSData = ...

// Create char array with the required size:
var dataToSentToPrinter = [CUnsignedChar](count: commandsToPrint.length, repeatedValue: 0)

// Fill with bytes from NSData object:
commandsToPrint.getBytes(&dataToSentToPrinter, length: sizeofValue(dataToSentToPrinter))

let dataToSentToPrinter = UnsafePointer<CUnsignedChar>(commandsToPrint.bytes)
let commandSize = commandsToPrint.length
var totalAmountWritten = 0

while totalAmountWritten < commandSize {
    let remaining = commandSize - totalAmountWritten
    let amountWritten = starPort.writePort(dataToSentToPrinter, totalAmountWritten, remaining)
    totalAmountWritten += amountWritten
    // ...
}