ios - 选择器没有已知的实例方法 - Obj-C

Question

出于某种原因，我在我的代码中遇到了这个错误并且无法解决。我正在尝试在我的应用程序中为类项目安装 QR 扫描仪。提前致谢。

ScannerViewController.h:

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>

@protocol ScannerViewControllerDelegate;

@interface ScannerViewController : ViewController    <AVCaptureMetadataOutputObjectsDelegate>

@property (nonatomic, weak) id<ScannerViewControllerDelegate> delegate;

@property (assign, nonatomic) BOOL touchToFocusEnabled;

- (BOOL) isCameraAvailable;
- (void) startScanning;
- (void) stopScanning;
- (void) setTorch:(BOOL) aStatus;

@end

@protocol AMScanViewControllerDelegate <NSObject>

@optional

- (void) scanViewController:(ScannerViewController *) aCtler didTapToFocusOnPoint:(CGPoint) aPoint;
- (void) scanViewController:(ScannerViewController *) aCtler didSuccessfullyScan:(NSString *) aScannedValue;

@end

ScannerViewController.m:

#import "ScannerViewController.h"


@interface ScannerViewController ()

@property (strong, nonatomic) AVCaptureDevice* device;
@property (strong, nonatomic) AVCaptureDeviceInput* input;
@property (strong, nonatomic) AVCaptureMetadataOutput* output;
@property (strong, nonatomic) AVCaptureSession* session;
@property (strong, nonatomic) AVCaptureVideoPreviewLayer* preview;

@end

@implementation ScannerViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle    *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
    }
    return self;
}

- (void)viewWillAppear:(BOOL)animated;
{
     [super viewWillAppear:animated];
    if(![self isCameraAvailable]) {
    [self setupNoCameraView];
    }
}

- (void) viewDidAppear:(BOOL)animated;
{
    [super viewDidAppear:animated];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    if([self isCameraAvailable]) {
        [self setupScanner];
    }
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)evt
{
    if(self.touchToFocusEnabled) {
        UITouch *touch=[touches anyObject];
        CGPoint pt= [touch locationInView:self.view];
        [self focus:pt];
    }
}

#pragma mark -
#pragma mark NoCamAvailable

- (void) setupNoCameraView;
{
    UILabel *labelNoCam = [[UILabel alloc] init];
    labelNoCam.text = @"No Camera available";
    labelNoCam.textColor = [UIColor blackColor];
    [self.view addSubview:labelNoCam];
    [labelNoCam sizeToFit];
    labelNoCam.center = self.view.center;
}

- (NSUInteger)supportedInterfaceOrientations;
{
    return UIInterfaceOrientationMaskLandscape;
}

- (BOOL)shouldAutorotate;
{
    return (UIDeviceOrientationIsLandscape([[UIDevice currentDevice]    orientation]));
}

- (void)didRotateFromInterfaceOrientation:    (UIInterfaceOrientation)fromInterfaceOrientation;
{
    if([[UIDevice currentDevice] orientation] ==    UIDeviceOrientationLandscapeLeft) {
        AVCaptureConnection *con = self.preview.connection;
        con.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
    } else {
        AVCaptureConnection *con = self.preview.connection;
        con.videoOrientation = AVCaptureVideoOrientationLandscapeLeft;
    }
}

#pragma mark -
#pragma mark AVFoundationSetup

- (void) setupScanner;
{
    self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    self.input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];

    self.session = [[AVCaptureSession alloc] init];

    self.output = [[AVCaptureMetadataOutput alloc] init];
    [self.session addOutput:self.output];
    [self.session addInput:self.input];

    [self.output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    self.output.metadataObjectTypes = @[AVMetadataObjectTypeQRCode];

    self.preview = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
    self.preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
    self.preview.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

    AVCaptureConnection *con = self.preview.connection;

    con.videoOrientation = AVCaptureVideoOrientationLandscapeLeft;

    [self.view.layer insertSublayer:self.preview atIndex:0];
}

#pragma mark -
#pragma mark Helper Methods

- (BOOL) isCameraAvailable;
{
    NSArray *videoDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    return [videoDevices count] > 0;
}

- (void)startScanning;
{
    [self.session startRunning];

}

- (void) stopScanning;
{
    [self.session stopRunning];
}

- (void) setTorch:(BOOL) aStatus;
{
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    [device lockForConfiguration:nil];
    if ( [device hasTorch] ) {
        if ( aStatus ) {
            [device setTorchMode:AVCaptureTorchModeOn];
        } else {
            [device setTorchMode:AVCaptureTorchModeOff];
        }
    }
    [device unlockForConfiguration];
}

- (void) focus:(CGPoint) aPoint;
{
    AVCaptureDevice *device = [AVCaptureDevice    defaultDeviceWithMediaType:AVMediaTypeVideo];
    if([device isFocusPointOfInterestSupported] &&
       [device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
        CGRect screenRect = [[UIScreen mainScreen] bounds];
        double screenWidth = screenRect.size.width;
        double screenHeight = screenRect.size.height;
        double focus_x = aPoint.x/screenWidth;
        double focus_y = aPoint.y/screenHeight;
        if([device lockForConfiguration:nil]) {
// Error here ------------------------
            if([self.delegate    respondsToSelector:@selector(scanViewController:didTapToFocusOnPoint:)]) {
                [self.delegate scanViewController:self     didTapToFocusOnPoint:aPoint];
            }
 // ------------------- End
            [device setFocusPointOfInterest:CGPointMake(focus_x,focus_y)];
            [device setFocusMode:AVCaptureFocusModeAutoFocus];
            if ([device isExposureModeSupported:AVCaptureExposureModeAutoExpose]){
                [device setExposureMode:AVCaptureExposureModeAutoExpose];
            }
            [device unlockForConfiguration];
        }
    }
}

#pragma mark -
#pragma mark AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects
fromConnection:(AVCaptureConnection *)connection
{
    for(AVMetadataObject *current in metadataObjects) {
        if([current isKindOfClass:[AVMetadataMachineReadableCodeObject class]]) {
//Error in this line here ---------------
            if([self.delegate respondsToSelector:@selector(scanViewController:didSuccessfullyScan:)]) {
                NSString *scannedValue =     [((AVMetadataMachineReadableCodeObject *) current) stringValue];
                [self.delegate scanViewController:self   didSuccessfullyScan:scannedValue];
// ----------------------------End
            }
        }
    }
}

@end

如果有人有比这更好的教程，请随时提供，因为由于某些原因很难找到。

引用教程: http://www.ama-dev.com/iphone-qr-code-library-ios-7/

Answer 1

我遗漏了您告诉编译器委托(delegate)是 的地方。