從Objective-C到Swift的轉換問題

Question

我正在嘗試將僅用Objective-C編寫的Apple自己的示例代碼轉換為Swift。

這就是目標C中的內容

。H

@import UIKit;

@class AVCaptureSession;

@interface AAPLPreviewView : UIView

@property (nonatomic) AVCaptureSession *session;

@end

.M

@import AVFoundation;

#import "AAPLPreviewView.h"

@implementation AAPLPreviewView

+ (Class)layerClass
{
    return [AVCaptureVideoPreviewLayer class];
}

- (AVCaptureSession *)session
{
    AVCaptureVideoPreviewLayer *previewLayer = (AVCaptureVideoPreviewLayer *)self.layer;
    return previewLayer.session;
}

- (void)setSession:(AVCaptureSession *)session
{
    AVCaptureVideoPreviewLayer *previewLayer = (AVCaptureVideoPreviewLayer *)self.layer;
    previewLayer.session = session;
}

@end

到目前為止，這是我想到的Swift：

import AVFoundation
import UIKit

class CamPreviewLayer: UIView
{
    var session: AVCaptureSession!
    override class func layerClass() -> AnyClass
    {
        return AVCaptureVideoPreviewLayer
    }

    func session() -> AVCaptureSession {
        var previewLayer: AVCaptureVideoPreviewLayer = self.layer as! AVCaptureVideoPreviewLayer
        return previewLayer.session
    }

    func setSession(session: AVCaptureSession) {
        let previewLayer: AVCaptureVideoPreviewLayer = self.layer as! AVCaptureVideoPreviewLayer
        previewLayer.session = session
    }
}

我的Swift代碼有3個錯誤。

Answer 1

您必須刪除var session: AVCaptureSession像這樣。

import AVFoundation
import UIKit

class AVPreviewView : UIView {
    override class func layerClass() -> AnyClass {
        return AVCaptureVideoPreviewLayer.self
    }
    func session () -> AVCaptureSession {
        return (self.layer as! AVCaptureVideoPreviewLayer).session
    }

    func setSession(session : AVCaptureSession) -> Void {
        (self.layer as! AVCaptureVideoPreviewLayer).session = session;
        (self.layer as! AVCaptureVideoPreviewLayer).videoGravity = AVLayerVideoGravityResizeAspect;

    }
}

希望對您有所幫助！