iOS:使用设置切换PHPhotoLibrary权限

Question

我正在检查相机卷的权限：

-(void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:YES];
    PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
    if (status != PHAuthorizationStatusNotDetermined) {
        // Access has not been determined.
        [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
            if (status == PHAuthorizationStatusAuthorized) {
                // do something
            }else {
                // Access has been denied.
            }
        }];
    }
}

它运行良好，但问题是，如果用户选择“不允许”，并希望切换到“允许”。

用户如何将权限切换到相机卷？

Answer 1

你可以要求你的用户打开权限，如果他们说“是的，我想打开这个权限”，那么你可以使用NSURL将它们直接传输到你的应用程序的首选项中，他们也可以通过单击状态栏左边的后退按钮返回到你的应用程序。

这里是将用户传输到应用程序首选项的代码：

NSURL *settingsUrl = [[NSURL alloc] initWithString:UIApplicationOpenSettingsURLString];
[[UIApplication sharedApplication] openURL:settingsUrl];

这里是我在iOS10 iPhone6s:中测试的完整代码

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:YES];
    PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
    if (status != PHAuthorizationStatusNotDetermined) {
        // Access has not been determined.
        [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
            if (status == PHAuthorizationStatusAuthorized) {
                // do something
            }else {
                // Access has been denied.
                UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Need Photo Permission"
                                                                               message:@"Using this app need photo permission, do you want to turn on it?"
                                                                        preferredStyle:UIAlertControllerStyleAlert];
                UIAlertAction *yesAction = [UIAlertAction actionWithTitle:@"YES" style:UIAlertActionStyleDefault
                                                                      handler:^(UIAlertAction * action) {
                                                                          NSURL *settingsUrl = [[NSURL alloc] initWithString:UIApplicationOpenSettingsURLString];
                                                                          [[UIApplication sharedApplication] openURL:settingsUrl];
                                                                      }];
                UIAlertAction *noAction = [UIAlertAction actionWithTitle:@"NO" style:UIAlertActionStyleCancel
                                                                 handler:^(UIAlertAction * action) {
                                                                 }];
                [alert addAction:yesAction];
                [alert addAction:noAction];
                [self presentViewController:alert animated:YES completion:nil];
            }
        }];
    }
}