Question

我只是将我的iOS应用程序代码更新为Swift 3，这一行让我感到高兴：

let dataProvider:CGDataProvider? = CGDataProviderCreateWithData(nil, maskImagePixelData!, maskImagePixelData!.count, nil)

在我之前使用的Swift版本中有效，现在它抛出了这个错误：

Nil与预期的参数类型不兼容＆＃39; CGDataProviderReleaseDataCallback＆＃39; （又名＆＃39; @convention（c）（可选＆lt; UnsafeMutableRawPointer＆gt;，UnsafeRawPointer，Int） - ＆gt; {}＆＃39;）

我找不到CGDataProviderCreateWithData（！）的文档，但签名也让我感到困惑：

CG_EXTERN CGDataProviderRef __nullable CGDataProviderCreateWithData(
    void * __nullable info, const void * cg_nullable data, size_t size,
    CGDataProviderReleaseDataCallback cg_nullable releaseData)

是否有nil的简单替代品，还是需要进入某种UnsafeMutableRawPointer？

Answer 1

知道了：

    let releaseMaskImagePixelData: CGDataProviderReleaseDataCallback = { (info: UnsafeMutableRawPointer?, data: UnsafeRawPointer, size: Int) -> () in
        // https://developer.apple.com/reference/coregraphics/cgdataproviderreleasedatacallback
        // N.B. 'CGDataProviderRelease' is unavailable: Core Foundation objects are automatically memory managed
        return
    }
    var dataProvider:CGDataProvider? = CGDataProvider(dataInfo: nil, data: maskImagePixelData!, size: maskImagePixelData!.count, releaseData: releaseMaskImagePixelData)

使用CGDataProvider.init替换CGDataProviderCreateWithData文档为here

Nil与预期参数类型不兼容可选<unsafemutablerawpointer>

1 个答案: