经过一些研究，看起来你不能做我想要的事情。以下是我编写的替代方案，可弹出对话框并自动打开设置应用程序（如果在iOS 8+上）。
一些注意事项：
- 自iOS 10以来，您需要在Info.plist中指定NSCameraUsageDescription键才能请求相机访问权限，否则您的应用程序将在运行时崩溃。
- 一旦用户更改了您的应用程序的任何权限，它将终止您的应用程序。请适当处理并保存用户点击“Go”按钮之前所需的任何数据。
- 在iOS 8和11之间的某个时刻，苹果不再要求用户触摸设置应用程序中的隐私单元格即可进入并更改相机设置。根据用户使用的iOS版本更改您在设置应用程序中指示用户执行的操作说明可能更好。如果有人想留言告诉我们确切的iOS版本变化时间，那就太棒了。
- 我们最后编辑这篇答案时，下面的代码在iOS 14.2上可以工作。
Swift 5.2：
在您的视图控制器顶部：
import AVFoundation
在打开相机视图之前：
@IBAction func goToCamera()
{
let status = AVCaptureDevice.authorizationStatus(for: .video)
switch (status)
{
case .authorized:
self.popCamera()
case .notDetermined:
AVCaptureDevice.requestAccess(for: .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)
@unknown default:
fatalError()
}
}
带有完成块的拒绝警报：
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: UIApplication.openSettingsURLString)!)
{
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: UIApplication.openSettingsURLString)!, options: [:], completionHandler: nil)
})
}
let alert = UIAlertController(title: "Error", message: alertText, preferredStyle: .alert)
alert.addAction(goAction)
self.present(alert, animated: true, completion: nil)
}
}
Objective-C:
在您的视图控制器顶部：
#import <AVFoundation/AVFoundation.h>
在打开相机视图之前：
- (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)
{
[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];
}
}
拒绝警报：
- (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];
}
UIAlertView的代理调用：
- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
if (alertView.tag == 3491832)
{
BOOL canOpenSettings = (&UIApplicationOpenSettingsURLString != NULL);
if (canOpenSettings)
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
}
}
