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ios - iPhone 相机，如何避免预览 View 上的相机叠加；如何知道何时进入预览 View ？

coder 2023-07-28 原文

在相机工作流程中，照片被捕获，在下一个屏幕上，我们称之为选择屏幕，您可以选择是使用这张照片还是重新拍摄。

我怎么知道相机何时进入预览 View ？

我的问题是我添加了一个按钮来访问相机胶卷，效果很好。障碍是，当拍照并进入预览 View (2. Camera View)时，按钮隐藏了“使用照片”选项。所以我不能选择它。我想在进入预览 View 时隐藏按钮，或者只是避免预览 View 。

在我的代码下面

摄像头屏幕.h

#import <UIKit/UIKit.h>
#import "CameraViewController.h"
#import <AssetsLibrary/AssetsLibrary.h>

@interface CamViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
@property (nonatomic, strong) UIImage *image;
@property (nonatomic, strong) UIImage *lastTakenImage;
- (IBAction)takePhoto:(id)sender;
- (IBAction)selectPhoto:(id)sender;
@end

CamViewScreen.m

#import "CamViewController.h"

@interface CamViewController ()

@end

@implementation CamViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

int isAction = 0; // Photo, 1: CameraRoll, 2: Cancel

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

        UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                              message:@"Device has no camera"
                                                             delegate:nil
                                                    cancelButtonTitle:@"OK"
                                                    otherButtonTitles: nil];

        [myAlertView show];

    }
    isAction = 0;
    [self cameraRoll];
}

-(void)viewDidAppear:(BOOL)animated {
    // isAction = 0 Photo, 1: CameraRoll, 2: Cancel
    DLog(@"###### isAction> %d", isAction);

    switch (isAction) {
        case 1:
            [self selectPhoto:nil];
            break;
        case 2:
            [self dismissViewControllerAnimated:NO completion:nil];
            break;
        default:
            [self takePhoto:nil];
            break;
    }
}

- (IBAction)takePhoto:(id)sender {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.allowsEditing = NO;
    picker.sourceType = UIImagePickerControllerSourceTypeCamera;
    picker.cameraOverlayView = [self addCameraRollButton];  // suggestion from omz

    // [self addCameraRollButton:picker.view];

    [self presentViewController:picker animated:YES completion:NULL];
}

-(void)prepareCameraRoll {
    isAction = 1;
    [self dismissViewControllerAnimated:NO completion:nil];

}

- (IBAction)selectPhoto:(id)sender {

    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.allowsEditing = YES;
    picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    [self presentViewController:picker animated:YES completion:NULL];
}

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

    UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
    self.image = chosenImage;

    isAction = 0;
    [picker dismissViewControllerAnimated:YES completion:NULL];
    [self performSegueWithIdentifier:@"toCameraView" sender:info];

}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {

    isAction = 2; // Cancel
    [picker dismissViewControllerAnimated:YES completion:NULL];


}
# pragma mark - for the cameraOverlayView // suggestion from omz
- (UIView *)addCameraRollButton {
    float startY = ([[UIScreen mainScreen] bounds].size.height == 568.0) ? 500.0 : 410.0;

    UIButton *rollButton = [UIButton buttonWithType:UIButtonTypeCustom];
    rollButton.frame = CGRectMake(230.0, startY, 60.0, 60.0);
    rollButton.backgroundColor = [UIColor clearColor];

    [rollButton setImage:self.lastTakenImage forState:UIControlStateNormal];
    rollButton.imageView.contentMode = UIViewContentModeScaleAspectFill;

    [rollButton addTarget:self action:@selector(prepareCameraRoll) forControlEvents:UIControlEventTouchUpInside];

    return rollButton;
}

# pragma mark - CameraRoll function and presentation
- (void)addCameraRollButton:(UIView *)picker {
    float startY = ([[UIScreen mainScreen] bounds].size.height == 568.0) ? 500.0 : 410.0;

    UIButton *rollButton = [UIButton buttonWithType:UIButtonTypeCustom];
    rollButton.frame = CGRectMake(230.0, startY, 60.0, 60.0);
    rollButton.backgroundColor = [UIColor clearColor];

    [rollButton setImage:self.lastTakenImage forState:UIControlStateNormal];
    rollButton.imageView.contentMode = UIViewContentModeScaleAspectFill;

    [rollButton addTarget:self action:@selector(prepareCameraRoll) forControlEvents:UIControlEventTouchUpInside];

    [picker addSubview:rollButton];
}

-(void)cameraRoll {
    ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];
    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos
                                 usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
                                     if (nil != group) {
                                         // be sure to filter the group so you only get photos
                                         [group setAssetsFilter:[ALAssetsFilter allPhotos]];

                                         [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop) {
                                             if (asset) {
                                                 ALAssetRepresentation *repr = [asset defaultRepresentation];
                                                 //  UIImage *img = [UIImage imageWithCGImage:[repr fullResolutionImage]];
                                                 UIImage *img = [UIImage imageWithCGImage:[repr fullScreenImage]];
                                                 [self setLastTakenImage:img];
                                                 *stop = YES;
                                             }
                                         }];
                                     }


                                     *stop = NO;
                                 } failureBlock:^(NSError *error) {
                                     NSLog(@"error: %@", error);
                                 }];
}


#pragma mark - Navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    CameraViewController *cvc = [segue destinationViewController];

    cvc.image = self.image;
    DLog(@"%@, cvcimage", cvc.image);
}
@end

最佳答案

找到解决方案。很难找到，但终于找到了。 UIImagePicker cameraOverlayView appears on Retake screen 中描述了该解决方案.此外，我为其他有同样问题的人添加了我的工作代码。

将 NSNotificationCenter 与 @"_UIImagePickerControllerUserDidCaptureItem" 和 @"_UIImagePickerControllerUserDidRejectItem" 一起使用是关键!

CamViewController.h

#import <UIKit/UIKit.h>
#import "CameraViewController.h"
#import <AssetsLibrary/AssetsLibrary.h>

@interface CamViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
@property (nonatomic, strong) UIImage *image;
@property (nonatomic, strong) UIImage *lastTakenImage;
@property (nonatomic, strong) UIImagePickerController *picker;
- (IBAction)takePhoto:(id)sender;
- (IBAction)selectPhoto:(id)sender;
@end

CamViewController.h

#import "CamViewController.h"

@interface CamViewController ()

@end

@implementation CamViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

int isAction = 0; // Photo, 1: CameraRoll, 2: Cancel

- (void)viewDidLoad
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleNotification:) name:@"_UIImagePickerControllerUserDidCaptureItem" object:nil ];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleNotification:) name:@"_UIImagePickerControllerUserDidRejectItem" object:nil ];

    [super viewDidLoad];
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

        UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                              message:@"Device has no camera"
                                                             delegate:nil
                                                    cancelButtonTitle:@"OK"
                                                    otherButtonTitles: nil];

        [myAlertView show];

    }
    isAction = 0;
    [self cameraRoll];
}

-(void)handleNotification:(NSNotification *)message {
    if ([[message name] isEqualToString:@"_UIImagePickerControllerUserDidCaptureItem"]) {
        // Remove overlay, so that it is not available on the preview view;
        self.picker.cameraOverlayView = nil;
    }
    if ([[message name] isEqualToString:@"_UIImagePickerControllerUserDidRejectItem"]) {
        // Retake button pressed on preview. Add overlay, so that is available on the camera again
        self.picker.cameraOverlayView = [self addCameraRollButton];
    }
}

-(void)viewDidAppear:(BOOL)animated {
    // isAction = 0: Photo, 1: CameraRoll, 2: Cancel
    DLog(@"###### isAction> %d", isAction);

    switch (isAction) {
        case 1:
            [self selectPhoto:nil];
            break;
        case 2:
            [self dismissViewControllerAnimated:NO completion:nil];
            break;
        default:
            [self takePhoto:nil];
            break;
    }
}

- (IBAction)takePhoto:(id)sender {
    self.picker = [[UIImagePickerController alloc] init];
    self.picker.delegate = self;
    self.picker.allowsEditing = YES; // if this is NO or missing, the image the image will not be in info[UIImagePickerControllerEditedImage]
    self.picker.sourceType = UIImagePickerControllerSourceTypeCamera;
    self.picker.cameraOverlayView = [self addCameraRollButton];

    [self presentViewController:self.picker animated:YES completion:NULL];
}

-(void)prepareCameraRoll {
    isAction = 1;
    [self dismissViewControllerAnimated:NO completion:nil];

}

- (IBAction)selectPhoto:(id)sender {

    self.picker = [[UIImagePickerController alloc] init];
    self.picker.delegate = self;
    self.picker.allowsEditing = YES;
    self.picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    [self presentViewController:self.picker animated:YES completion:NULL];
}

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

    self.image = info[UIImagePickerControllerEditedImage]; 

    isAction = 0;
    [picker dismissViewControllerAnimated:YES completion:NULL];
    [self performSegueWithIdentifier:@"toCameraView" sender:info];

}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {

    isAction = 2; // Cancel
    [picker dismissViewControllerAnimated:YES completion:NULL];

}

# pragma mark - CameraRoll function and presentation
- (UIView *)addCameraRollButton {
    float startY = ([[UIScreen mainScreen] bounds].size.height == 568.0) ? 500.0 : 410.0;

    UIButton *rollButton = [UIButton buttonWithType:UIButtonTypeCustom];
    rollButton.frame = CGRectMake(230.0, startY, 60.0, 60.0);
    rollButton.backgroundColor = [UIColor clearColor];

    [rollButton setImage:self.lastTakenImage forState:UIControlStateNormal];
    rollButton.imageView.contentMode = UIViewContentModeScaleAspectFill;

    [rollButton addTarget:self action:@selector(prepareCameraRoll) forControlEvents:UIControlEventTouchUpInside];

    return rollButton;
}

-(void)cameraRoll {
    // have to import assetlibrary framework!!!
    ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];
    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos
                                 usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
                                     if (nil != group) {
                                         // be sure to filter the group so you only get photos
                                         [group setAssetsFilter:[ALAssetsFilter allPhotos]];

                                         [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop) {
                                             if (asset) {
                                                 ALAssetRepresentation *repr = [asset defaultRepresentation];
                                                 //  UIImage *img = [UIImage imageWithCGImage:[repr fullResolutionImage]];
                                                 UIImage *img = [UIImage imageWithCGImage:[repr fullScreenImage]];
                                                 [self setLastTakenImage:img];
                                                 *stop = YES;
                                             }
                                         }];
                                     }


                                     *stop = NO;
                                 } failureBlock:^(NSError *error) {
                                     NSLog(@"error: %@", error);
                                 }];
}


#pragma mark - Navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    CameraViewController *cvc = [segue destinationViewController];

    cvc.image = self.image;
    DLog(@"%@, cvcimage", cvc.image);
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

@end

关于ios - iPhone 相机，如何避免预览 View 上的相机叠加；如何知道何时进入预览 View ？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23795453/

View何时selfpickerrollButtoniosiphoneobjective-ccamerauiimagepickercontroller

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