无法立即呈现图像选择器

Question

我有一个标签栏控制器，当我点击第三个标签栏按钮时，我会显示一个UIViewcontroller。在这个 vc 的 viewWillAppear 中，我展示了一个运行良好的 UIImagepickerController。问题是我打开视图时无法立即在屏幕上显示它。首先出现 vc，然后在 0.4-0.5 秒后出现图像选择器。所以我想先展示图像选择器，然后在用户拍摄图像后展示 vc。我也尝试从viewDidLoad 和viewWillAppear 调用选择器，但没有任何改变。

- (void)viewWillAppear:(BOOL)animated {

    [super viewWillAppear:animated];

    if (imagePickerWasPresented == NO)
    {
        imagePickerWasPresented = YES;

        self.imagePicker = [[UIImagePickerController alloc] init];
        self.imagePicker.delegate = self;
        self.imagePicker.allowsEditing = YES;


        self.imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
        self.imagePicker.mediaTypes = [NSArray arrayWithObject:(NSString *)kUTTypeImage];

        [self presentViewController:self.imagePicker animated:NO completion:nil];
    }
}

我是不是在错误的地方调用它？

Answer 1

不，你在合适的地方调用它，这就是 iOS 的做法；如果您将多个模态呈现在彼此之上，则一个接一个呈现，包括动画。一个可以解决您的问题的解决方案是提供一个 UINavigationController 而不是您的 UIViewController。将导航控制器设置为将 ViewController 作为根视图控制器，但还将您的 imagepickercontroller 推送到堆栈上。展示这个导航控制器，它应该直接进入你的图像选择器控制器。否则，请尝试同时显示 uiviewcontroller 和 imagepickercontroller，并将动画设置为 NO，看看是否有效。

Answer 2

试试这个，看看你有多接近然后适应你的需求。当我对其进行快速测试时，它似乎可以满足您的要求。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] ;

    UIViewController * vc = [[UIViewController alloc] init];

    vc.view.backgroundColor = [UIColor whiteColor];

    UINavigationController * navigationController = [[UINavigationController alloc] init];
    [navigationController pushViewController:vc animated:NO];


    UITabBarController * tabBarController = [[UITabBarController alloc] init];
    NSArray* controllers = [NSArray arrayWithObjects:navigationController, nil];
    tabBarController.viewControllers = controllers;

    tabBarController.delegate = self;

    UIImagePickerController *imagePicker =
    [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.sourceType =
    UIImagePickerControllerSourceTypePhotoLibrary;
    imagePicker.mediaTypes = [NSArray arrayWithObjects:
                          (NSString *) kUTTypeImage,
                          nil];
    imagePicker.allowsEditing = NO;

    self.window.rootViewController = tabBarController;

    [self.window makeKeyAndVisible];

    [vc presentViewController:imagePicker animated:NO completion:nil];

    return YES;

}

Answer 3

我遇到了同样的问题 - 不是先调用 VC，然后再调用 UIImagePicker，而是直接调用 UIImagePicker。

当你拍完照片/视频后：

- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {}

您将使用这个标准委托方法，从这里调用 VC。这样，您将立即转到 ImagePicker，并且只有一个过渡，您会选择在之后对所拍摄的内容做一些事情，这不那么令人沮丧/难看。

Answer 4

UIImage 作为 PopOver

图库模式：

BOOL hasGallery = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary];
UIImagePickerController* picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.sourceType = hasGalleryt ? UIImagePickerControllerSourceTypePhotoLibrary :    UIImagePickerControllerSourceTypePhotoLibrary;
if (self.popoverController != nil)
{
    [self.popoverController dismissPopoverAnimated:YES];
    self.popoverController=nil;
}
self.popoverController = [[UIPopoverController alloc] initWithContentViewController:picker];
CGRect popoverRect = [self.view convertRect:[self.imageView frame]
                                   fromView:[self.imageView superview]];
popoverRect.size.width = MIN(popoverRect.size.width, 300) ;
popoverRect.origin.x = popoverRect.origin.x;
[self.popoverController
 presentPopoverFromRect:popoverRect
 inView:self.view
 permittedArrowDirections:UIPopoverArrowDirectionAny
 animated:YES];

拍照模式：

BOOL hasCamera = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];
UIImagePickerController* picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.sourceType = hasCamera ? UIImagePickerControllerSourceTypeCamera :    UIImagePickerControllerSourceTypePhotoLibrary;
if (self.popoverController != nil)
{
    [self.popoverController dismissPopoverAnimated:YES];
    self.popoverController = nil;
}
self.popoverController = [[UIPopoverController alloc] initWithContentViewController:picker];
CGRect popoverRect = [self.view convertRect:[self.imageView frame]
                                   fromView:[self.imageView superview]];
popoverRect.size.width = MIN(popoverRect.size.width, 300) ;
popoverRect.origin.x = popoverRect.origin.x;
[self.popoverController
 presentPopoverFromRect:popoverRect
 inView:self.view
 permittedArrowDirections:UIPopoverArrowDirectionAny
 animated:YES];

记得给.h文件@interface代表，像这样：

@interface the UIViewController: UIViewController <UIPopoverControllerDelegate, UIImagePickerControllerDelegate>