如何在swift中编写这个void objective-c函数

Question

我发现了代码，我想在一个快速的ios应用程序中使用，但我很难快速写入它。

-(void) captureOutput:(AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection*)connection 
{ 
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
    CGSize imageSize = CVImageBufferGetEncodedSize(imageBuffer); 
    // also in the 'mediaSpecific' dict of the sampleBuffer 

    NSLog(@"frame captured at %.fx%.f", imageSize.width, imageSize.height); 
} 

这只是我遇到的函数声明，函数的内容应该更容易。我不习惯的语法：

-(void) captureOutput:(AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection*)connection 

我尝试：

我开始尝试写这样的，但没事的时候就在()内自动完成我意识到这是绝对错误的：

func captureOutput(AVCaptureOutput(didOutputSampleBuffer:)) { 

} 

Answer 1

你可以找到在AVCaptureVideoDataOutputSampleBufferDelegate Protocol Reference，在声明这样正确的声明：

optional func captureOutput(_ captureOutput: AVCaptureOutput!, 
    didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, 
    fromConnection connection: AVCaptureConnection!) 

在你的方法定义你不会写optional，虽然：

class MyDelegate: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate { 

    func captureOutput(captureOutput:AVCaptureOutput, 
     didOutputSampleBuffer sampleBuffer:CMSampleBuffer, 
     fromConnection connection:AVCaptureConnection) { 

      let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) 
      let imageSize = CVImageBufferGetEncodedSize(imageBuffer) 

      NSLog("frame captured at %.fx%.f", imageSize.width, imageSize.height) 
    } 

}