【Unity×iOS】カメラロールから画像を選択して表示・アップロードする方法｜Objective-C連携で実現

#import <UIKit/UIKit.h>
#import <MobileCoreServices/MobileCoreServices.h>
#import "UnityAppController.h"

@interface ImagePickerDelegate : NSObject <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
@end

@implementation ImagePickerDelegate

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImage *image = info[UIImagePickerControllerOriginalImage];
    NSData *imageData = UIImagePNGRepresentation(image);
    NSString *base64String = [imageData base64EncodedStringWithOptions:0];

    UnitySendMessage("ImageReceiver", "OnImageSelected", [base64String UTF8String]);

    [picker dismissViewControllerAnimated:YES completion:nil];
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [picker dismissViewControllerAnimated:YES completion:nil];
}

@end

static ImagePickerDelegate* pickerDelegate = nil;

extern "C" void OpenImagePicker()
{
    UIViewController *rootVC = UnityGetGLViewController();
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    picker.delegate = pickerDelegate = [[ImagePickerDelegate alloc] init];

    [rootVC presentViewController:picker animated:YES completion:nil];
}

using UnityEngine;
using System.Runtime.InteropServices;

public class ImageReceiver : MonoBehaviour
{
    [DllImport("__Internal")]
    private static extern void OpenImagePicker();

    public Renderer targetRenderer;

    public void PickImage()
    {
#if UNITY_IOS && !UNITY_EDITOR
        OpenImagePicker();
#else
        Debug.Log("実機でのみ動作します。");
#endif
    }

    public void OnImageSelected(string base64)
    {
        byte[] imageData = System.Convert.FromBase64String(base64);
        Texture2D texture = new Texture2D(2, 2);
        texture.LoadImage(imageData);
        targetRenderer.material.mainTexture = texture;
    }
}

public class UIController : MonoBehaviour
{
    public ImageReceiver imageReceiver;

    public void OnPickPhotoButtonPressed()
    {
        imageReceiver.PickImage();
    }
}