经过一些研究，您似乎无法做我想做的事。如果在 iOS 8+ 上，这是我编写的用于弹出对话框并自动打开设置应用程序的替代方法。
一些注意事项：
- 从 iOS 10 开始，您需要在 Info.plist 中指定
NSCameraUsageDescription 键才能请求相机访问权限，否则您的应用将在运行时崩溃。
- 一旦用户更改了您应用的任何权限，它就会终止您的应用。在用户点击“开始”按钮之前，相应地处理并保存任何需要的数据。
- 在 iOS 8 和 11 之间的某个时间点，Apple 不再要求用户触摸设置应用程序中的隐私单元来访问和更改相机设置。您可能希望根据用户使用的 iOS 版本更改有关用户应该在“设置”应用中执行的操作的说明。如果有人想在下方发表评论，告诉我们具体的 iOS 版本发生了哪些变化，那就太好了。
- 截至本答案的最后一次编辑，以下代码适用于 iOS 14.2。
Swift 5.2：
在视图控制器的顶部：
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)
}
}
目标-C：
在视图控制器的顶部：
#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)
{
// 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];
}
对 UIAlertView 的委托调用：
- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
if (alertView.tag == 3491832)
{
BOOL canOpenSettings = (&UIApplicationOpenSettingsURLString != NULL);
if (canOpenSettings)
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
}
}