if ( [[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0){
//check whether the permission open for user in settings
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if (authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied)
{
CMAlertView *alert = [[CMAlertView alloc]init];
[alert setAlertViewFrameWithX:self.localView.frame.size.width/8 withY:self.localView.bounds.size.height/2 withW:self.localView.frame.size.width - self.localView.frame.size.width/4 withH:100];
[alert setImage:@"01_login_alerticon@2x.png" withOrignalx:20 withY:30 withW:30 withH:30];
[alert setLabelWithText:NSLocalizedStringFromTable(@"alert_view_please_open_camera_visit_permission", @"StringInfo", nil) withX:50 withY:15 withW:180 withH:50];
[alert setFont:[UIFont systemFontOfSize:18.0f] withColor:[UIColor whiteColor]];
[alert setAlertViewBackgroundColor:[UIColor colorWithRed:68/255.0f green:153/255.0f blue:181/255.0f alpha:1.0]];
[alert setAlertViewDisplayType:@"Info"];
[alert show];
[alert release];
}
else{
//present the camera view
UIImagePickerController *picker = [[UIImagePickerController alloc] init];//initial
self.imagePickerController = picker;
[picker release];
self.imagePickerController.delegate = self;
self.imagePickerController.allowsEditing = YES;//set editable
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
self.imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
}else{
self.imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
}
[self presentViewController:self.imagePickerController animated:YES completion:nil];//enter camera
}
ios7.1后setting中没有开启相机服务应用程序相机预览黑屏问题,布布扣,bubuko.com
ios7.1后setting中没有开启相机服务应用程序相机预览黑屏问题
原文：http://www.cnblogs.com/lisa090818/p/3891907.html