检查 AVAuthorizationStatus并正确处理案件。

NSString *mediaType = AVMediaTypeVideo;
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];
if(authStatus == AVAuthorizationStatusAuthorized) {
// do your logic
} else if(authStatus == AVAuthorizationStatusDenied){
// denied
} else if(authStatus == AVAuthorizationStatusRestricted){
// restricted, normally won't happen
} else if(authStatus == AVAuthorizationStatusNotDetermined){
// not determined?!
[AVCaptureDevice requestAccessForMediaType:mediaType completionHandler:^(BOOL granted) {
if(granted){
NSLog(@"Granted access to %@", mediaType);
} else {
NSLog(@"Not granted access to %@", mediaType);
}
}];
} else {
// impossible, unknown authorization status
}

更新版的斯威夫特4

务必:

import AVFoundation

下面的代码检查所有可能的权限状态:

let cameraMediaType = AVMediaType.video
let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatus(for: cameraMediaType)
    

switch cameraAuthorizationStatus {
case .denied: break
case .authorized: break
case .restricted: break


case .notDetermined:
// Prompting user for the permission to use the camera.
AVCaptureDevice.requestAccess(for: cameraMediaType) { granted in
if granted {
print("Granted access to \(cameraMediaType)")
} else {
print("Denied access to \(cameraMediaType)")
}
}
}

从 iOS10开始，您需要指定 在 Info.plist 中设置 NSCameraUsageDescription键，以便能够请求摄像头访问，否则应用程序将在运行时崩溃。见 需要使用说明的 API。

来自 Apple Developer 论坛的一个有趣的旁注:

如果用户切换你的应用程序，系统实际上会杀死你的应用程序 访问设置中的 相机。同样适用于任何受保护的 设置→隐私部分中的 datacclass。

斯威夫特: 使用 AVFoundation

1. 添加 AVFoundation 到目标-> 构建阶段-> 链接二进制与库。
2. 在 ViewController 上导入 AVFoundation。
3. 在 Info.plist 上，添加以下内容:

4. 视图控制器:

@ IBAction func cameraButtonClick (sender: AnyObject){

let authorizationStatus = AVCaptureDevice.authorizationStatusForMediaType(AVMediaTypeVideo)
print(authorizationStatus.rawValue)


if AVCaptureDevice.authorizationStatusForMediaType(AVMediaTypeVideo) ==  AVAuthorizationStatus.Authorized{
self.openCameraAfterAccessGrantedByUser()
}
else
{
print("No Access")


dispatch_async(dispatch_get_main_queue()) { [unowned self] in
AVCaptureDevice.requestAccessForMediaType(AVMediaTypeVideo, completionHandler: { (granted :Bool) -> Void in
if granted == true
{
// User granted
self.openCameraAfterAccessGrantedByUser()
}
else
{
// User Rejected
alertToEncourageCameraAccessWhenApplicationStarts()
}
});
}
}




//Open camera


func openCameraAfterAccessGrantedByUser()
{
if(UIImagePickerController .isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)){
self.cameraAndGalleryPicker!.sourceType = UIImagePickerControllerSourceType.Camera
cameraAndGalleryPicker?.delegate = self
cameraAndGalleryPicker?.allowsEditing =  false
cameraAndGalleryPicker!.cameraCaptureMode = .Photo
cameraAndGalleryPicker!.modalPresentationStyle = .FullScreen
presentViewController(self.cameraAndGalleryPicker!, animated: true, completion: nil)
}
else
{


}
}


//Show Camera Unavailable Alert


func alertToEncourageCameraAccessWhenApplicationStarts()
{
//Camera not available - Alert
let cameraUnavailableAlertController = UIAlertController (title: "Camera Unavailable", message: "Please check to see if it is disconnected or in use by another application", preferredStyle: .Alert)


let settingsAction = UIAlertAction(title: "Settings", style: .Destructive) { (_) -> Void in
let settingsUrl = NSURL(string:UIApplicationOpenSettingsURLString)
if let url = settingsUrl {
dispatch_async(dispatch_get_main_queue()) {
UIApplication.sharedApplication().openURL(url)
}


}
}
let cancelAction = UIAlertAction(title: "Okay", style: .Default, handler: nil)
cameraUnavailableAlertController .addAction(settingsAction)
cameraUnavailableAlertController .addAction(cancelAction)
self.window?.rootViewController!.presentViewController(cameraUnavailableAlertController , animated: true, completion: nil)
}

作为@Raptor 回答的补充，应该提到以下几点。从 iOS10开始，您可能会收到以下错误: This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.

要解决这个问题，请确保按照以下方式处理主线程的结果(Swift 3) :

private func showCameraPermissionPopup() {
let cameraMediaType = AVMediaTypeVideo
let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatus(forMediaType: cameraMediaType)


switch cameraAuthorizationStatus {
case .denied:
NSLog("cameraAuthorizationStatus=denied")
break
case .authorized:
NSLog("cameraAuthorizationStatus=authorized")
break
case .restricted:
NSLog("cameraAuthorizationStatus=restricted")
break
case .notDetermined:
NSLog("cameraAuthorizationStatus=notDetermined")


// Prompting user for the permission to use the camera.
AVCaptureDevice.requestAccess(forMediaType: cameraMediaType) { granted in
DispatchQueue.main.sync {
if granted {
// do something
} else {
// do something else
}
}
}
}
}

迅捷解决方案

extension AVCaptureDevice {
enum AuthorizationStatus {
case justDenied
case alreadyDenied
case restricted
case justAuthorized
case alreadyAuthorized
case unknown
}


class func authorizeVideo(completion: ((AuthorizationStatus) -> Void)?) {
AVCaptureDevice.authorize(mediaType: AVMediaType.video, completion: completion)
}


class func authorizeAudio(completion: ((AuthorizationStatus) -> Void)?) {
AVCaptureDevice.authorize(mediaType: AVMediaType.audio, completion: completion)
}


private class func authorize(mediaType: AVMediaType, completion: ((AuthorizationStatus) -> Void)?) {
let status = AVCaptureDevice.authorizationStatus(for: mediaType)
switch status {
case .authorized:
completion?(.alreadyAuthorized)
case .denied:
completion?(.alreadyDenied)
case .restricted:
completion?(.restricted)
case .notDetermined:
AVCaptureDevice.requestAccess(for: mediaType, completionHandler: { (granted) in
DispatchQueue.main.async {
if granted {
completion?(.justAuthorized)
} else {
completion?(.justDenied)
}
}
})
@unknown default:
completion?(.unknown)
}
}
}

然后为了使用它

AVCaptureDevice.authorizeVideo(completion: { (status) in
//Your work here
})

首先在 Info.plist 中指定 NSCameraUsageDescription 键。 然后检查 AVAuthorizationStatus if Authorated 然后显示 UIImagePickerController。