iphone - AVCaptureSession 之前应为 "("

Question

当我尝试构建我的应用程序时，XCode 向我显示此错误

AVCaptureSession 之前应有“(”

有人可以帮我解决这个警告吗？这是我的代码:

ViewController.h

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface ViewController : UIViewController
{
}

- (IBAction)SwitchON_Flash;
- (void)setTorchSession:(AVCaptureSession *)CaptureSession;

@end

ViewController.m

#import "ViewController.h"

@implementation ViewController

UIAlertView *NoFlash;

- (IBAction)SwitchON_Flash
{
    AVCaptureDevice *Device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    if ([Device hasTorch] && [Device hasFlash])
    {
        if (Device.torchMode == AVCaptureTorchModeOff)
        {
            AVCaptureDevice *Device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
            AVCaptureDeviceInput *FlashInput = [AVCaptureDeviceInput deviceInputWithDevice:device error: nil];
            AVCaptureVideoDataOutput *VideoOutput = [[AVCaptureVideoDataOutput alloc] init];
            AVCaptureSession *CaptureSession = [[AVCaptureSession alloc] init];
            [CaptureSession beginConfiguration];
            [CaptureSession addInput:FlashInput];
            [CaptureSession addOutput:VideoOutput];
            [CaptureSession commitConfiguration];
            [CaptureSession startRunning];
            [Device lockForConfiguration:nil];
            [Device setTorchMode:AVCaptureTorchModeOn];
            [Device setFlashMode:AVCaptureFlashModeOn];
            [Device unlockForConfiguration];
            [self setTorchSession:CaptureSession];
            [CaptureSession release];
            [VideoOutput release];
        }

        else
        {
            [torchSession stopRunning];
        }

    }

    else
    {
        NoFlash = [[UIAlertView alloc] initWithTitle:@"Uh-Oh"
                                             message:@"Your device doesn't have a flash camera"
                                            delegate:nil
                                   cancelButtonTitle:@"mhmm, OK"
                                   otherButtonTitles:nil];
        NoFlash.delegate = self;
        [NoFlash show];
        [NoFlash release];          
    }   
    }

- (void)setTorchSession:(AVCaptureSession *)CaptureSession <== /// ERROR HERE ///
{
}

谢谢!

Answer 1

UIViewController 默认情况下没有该方法。您没有该方法的实现，因此它会向您发出此警告。如果您尝试运行此代码 - 您将收到“未知选择器发送到实例”错误。

您必须在 View Controller 中为 torchSession 添加属性或实现该特定方法。