有没有办法让用户在iOS上拒绝后才能访问相机？

Question

我正在使用此代码,但遗憾的是它不起作用.

在用户拒绝摄像头访问后,我想让他们在下次尝试加载时再次使用摄像头(在这种情况下,它是使用摄像头视图的条形码扫描仪).我总是得到AVAuthorizationStatusDenied,然后granted总是自动返回,NO即使我在代码中再次要求它.

我的许多用户都在给我发电子邮件说"当我尝试条形码扫描时我的屏幕是黑色的",这是因为他们因某些原因拒绝了相机访问.我希望能够再次提示他们,因为很可能拒绝这是一个错误.

有可能这样做吗？

    AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    if(authStatus == AVAuthorizationStatusAuthorized)
    {
        NSLog(@"%@", @"You have camera access");
    }
    else if(authStatus == AVAuthorizationStatusDenied)
    {
        NSLog(@"%@", @"Denied camera access");

        [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
            if(granted){
                NSLog(@"Granted access to %@", AVMediaTypeVideo);
            } else {
                NSLog(@"Not granted access to %@", AVMediaTypeVideo);
            }
        }];
    }
    else if(authStatus == AVAuthorizationStatusRestricted)
    {
        NSLog(@"%@", @"Restricted, normally won't happen");
    }
    else if(authStatus == AVAuthorizationStatusNotDetermined)
    {
        NSLog(@"%@", @"Camera access not determined. Ask for permission.");

        [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
            if(granted){
                NSLog(@"Granted access to %@", AVMediaTypeVideo);
            } else {
                NSLog(@"Not granted access to %@", AVMediaTypeVideo);
            }
        }];
    }
    else
    {
        NSLog(@"%@", @"Camera access unknown error.");
    }

Answer 1

经过一些研究,看起来你不能做我想做的事.如果在iOS 8+上,我编码弹出对话框并自动打开"设置"应用程序.

一些说明:

• 从iOS 10开始,您需要NSCameraUsageDescription在Info.plist中指定密钥以便能够请求摄像头访问,否则您的应用程序将在运行时崩溃.
• 用户更改您的应用的任何权限后,它将终止您的应用.在用户点击"开始"按钮之前,相应地处理并保存所需的数据.
• 在iOS 8和11之间的某个时刻,Apple不再要求用户触摸设置应用中的隐私单元格以进入和更改相机设置.您可能希望根据用户使用的iOS版本更改用户在"设置"应用中应执行的操作的说明.如果有人想在下面发表评论,告诉我们所有改变的iOS版本,那将是非常棒的.

斯威夫特4:

在视图控制器的顶部:

import AVFoundation

在打开摄像机视图之前:

@IBAction func goToCamera()
{
    let status = AVCaptureDevice.authorizationStatus(for: AVMediaType.video)
    switch (status)
    {
    case .authorized:
        self.popCamera()

    case .notDetermined:
        AVCaptureDevice.requestAccess(for: AVMediaType.video) { (granted) in
            if (granted)
            {
                self.popCamera()
            }
            else
            {
                self.camDenied()
            }
        }

    case .denied:
        self.camDenied()

    case .restricted:
        let alert = UIAlertController(title: "Restricted",
                                      message: "You've been restricted from using the camera on this device. Without camera access this feature won't work. Please contact the device owner so they can give you access.",
                                      preferredStyle: .alert)

        let okAction = UIAlertAction(title: "OK", style: .default, handler: nil)
        alert.addAction(okAction)
        self.present(alert, animated: true, completion: nil)
    }
}

完成阻止拒绝警报:

func camDenied()
{
    DispatchQueue.main.async
        {
            var alertText = "It looks like your privacy settings are preventing us from accessing your camera to do barcode scanning. You can fix this by doing the following:\n\n1. Close this app.\n\n2. Open the Settings app.\n\n3. Scroll to the bottom and select this app in the list.\n\n4. Turn the Camera on.\n\n5. Open this app and try again."

            var alertButton = "OK"
            var goAction = UIAlertAction(title: alertButton, style: .default, handler: nil)

            if UIApplication.shared.canOpenURL(URL(string: UIApplicationOpenSettingsURLString)!)
            {
                alertText = "It looks like your privacy settings are preventing us from accessing your camera to do barcode scanning. You can fix this by doing the following:\n\n1. Touch the Go button below to open the Settings app.\n\n2. Turn the Camera on.\n\n3. Open this app and try again."

                alertButton = "Go"

                goAction = UIAlertAction(title: alertButton, style: .default, handler: {(alert: UIAlertAction!) -> Void in
                    UIApplication.shared.open(URL(string: UIApplicationOpenSettingsURLString)!, options: [:], completionHandler: nil)
                })
            }

            let alert = UIAlertController(title: "Error", message: alertText, preferredStyle: .alert)
            alert.addAction(goAction)
            self.present(alert, animated: true, completion: nil)
    }
}

Objective-C的:

在视图控制器的顶部:

#import <AVFoundation/AVFoundation.h>

在打开摄像机视图之前:

- (IBAction)goToCamera
{
    AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    if(authStatus == AVAuthorizationStatusAuthorized)
    {
        [self popCamera];
    }
    else if(authStatus == AVAuthorizationStatusNotDetermined)
    {
        NSLog(@"%@", @"Camera access not determined. Ask for permission.");

        [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted)
        {
            if(granted)
            {
                NSLog(@"Granted access to %@", AVMediaTypeVideo);
                [self popCamera];
            }
            else
            {
                NSLog(@"Not granted access to %@", AVMediaTypeVideo);
                [self camDenied];
            }
        }];
    }
    else if (authStatus == AVAuthorizationStatusRestricted)
    {
        // My own Helper class is used here to pop a dialog in one simple line.
        [Helper popAlertMessageWithTitle:@"Error" alertText:@"You've been restricted from using the camera on this device. Without camera access this feature won't work. Please contact the device owner so they can give you access."];
    }
    else
    {
        [self camDenied];
    }
}

拒绝提醒:

- (void)camDenied
{
    NSLog(@"%@", @"Denied camera access");

    NSString *alertText;
    NSString *alertButton;

    BOOL canOpenSettings = (&UIApplicationOpenSettingsURLString != NULL);
    if (canOpenSettings)
    {
        alertText = @"It looks like your privacy settings are preventing us from accessing your camera to do barcode scanning. You can fix this by doing the following:\n\n1. Touch the Go button below to open the Settings app.\n\n2. Turn the Camera on.\n\n3. Open this app and try again.";

        alertButton = @"Go";
    }
    else
    {
        alertText = @"It looks like your privacy settings are preventing us from accessing your camera to do barcode scanning. You can fix this by doing the following:\n\n1. Close this app.\n\n2. Open the Settings app.\n\n3. Scroll to the bottom and select this app in the list.\n\n4. Turn the Camera on.\n\n5. Open this app and try again.";

        alertButton = @"OK";
    }

    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle:@"Error"
                          message:alertText
                          delegate:self
                          cancelButtonTitle:alertButton
                          otherButtonTitles:nil];
    alert.tag = 3491832;
    [alert show];
}

委托调用UIAlertView:

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    if (alertView.tag == 3491832)
    {
        BOOL canOpenSettings = (&UIApplicationOpenSettingsURLString != NULL);
        if (canOpenSettings)
            [[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
    }
}

Answer 2

一旦他们拒绝相机访问,用户可以在"设置"中为您的应用授权使用相机.按照设计,您无法在自己的代码中覆盖它.

您可以使用以下示例代码检测此案例,然后向用户解释如何修复它:iOS 7 UIImagePickerController Camera No Image

NSString *mediaType = AVMediaTypeVideo; // Or AVMediaTypeAudio

AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];

// The user has explicitly denied permission for media capture.
else if(authStatus == AVAuthorizationStatusDenied){
    NSLog(@"Denied");
}