如何在swift中編寫這個void objective-c函數

Question

我發現了代碼，我想在一個快速的ios應用程序中使用，但我很難快速寫入它。

-(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); 
} 

這只是我遇到的函數聲明，函數的內容應該更容易。我不習慣的語法：

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

我嘗試：

我開始嘗試寫這樣的，但沒事的時候就在()內自動完成我意識到這是絕對錯誤的：

func captureOutput(AVCaptureOutput(didOutputSampleBuffer:)) { 

} 

Answer 1

你可以找到在AVCaptureVideoDataOutputSampleBufferDelegate Protocol Reference，在聲明這樣正確的聲明：

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

在你的方法定義你不會寫optional，雖然：

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) 
    } 

}