ios - 如何在 Swift 中使用 'compression_encode_buffer'？

Question

我正在使用 Swift 的压缩库将图像压缩为 NSData。这是代码:

var imageCompressed:NSData
compression_encode_buffer( imageCompressed ,800000 , imageSelected , size , NULL , COMPRESSION_LZMA )

我收到以下错误消息:

Cannot convert value of type NSData to expected argument type UnsafeMutablePointer

Answer 1

我想你想要的是这样的(imageSelected 和 imageCompressed 被假定为 Swift 3 Data 对象):

imageSelected.withUnsafeBytes {(fromBytes: UnsafePointer<UInt8>) -> Void in
    imageCompressed.withUnsafeMutableBytes {(toBytes: UnsafeMutablePointer<UInt8>) -> Void in
        compression_encode_buffer(toBytes, toSize, fromBytes, fromSize, nil, COMPRESSION_LZMA)
    }
}