Upload image from ios device using Firebase - objective c

Question

I'm a newbie to ios development. I'm trying to follow the official documentation of Firebase to implement an image uploading function. But I encountered the following error:

2018-07-20 17:27:43.084497-0700 Geographical_Photo_Map[71118:36381409] -[NSURL _fastCStringContents:]: unrecognized selector sent to instance 0x6040012f2380
2018-07-20 17:27:43.090438-0700 Geographical_Photo_Map[71118:36381409] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSURL _fastCStringContents:]: unrecognized selector sent to instance 0x6040012f2380'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000011271712b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000011185ef41 objc_exception_throw + 48
    2   CoreFoundation                      0x0000000112798024 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   CoreFoundation                      0x0000000112699f78 ___forwarding___ + 1432
    4   CoreFoundation                      0x0000000112699958 _CF_forwarding_prep_0 + 120
    5   libsystem_trace.dylib               0x00000001138ac70b os_log_shim_with_CFString + 66
    6   CoreFoundation                      0x00000001126ed96f _CFLogvEx3 + 239
    7   Foundation                          0x000000011088030b _NSLogv + 104
    8   Foundation                          0x000000011086c023 NSLog + 132
    9   Geographical_Photo_Map              0x000000010f119c08 -[ViewController imagePickerController:didFinishPickingMediaWithInfo:] + 216
    10  UIKit                               0x0000000113e36def -[UIImagePickerController _imagePickerDidCompleteWithInfo:] + 127
    11  UIKit                               0x0000000113e36709 __60-[UIImagePickerController didSelectMediaWithInfoDictionary:]_block_invoke + 42
    12  libdispatch.dylib                   0x00000001135c12f7 _dispatch_call_block_and_release + 12
    13  libdispatch.dylib                   0x00000001135c233d _dispatch_client_callout + 8
    14  libdispatch.dylib                   0x00000001135cd5f9 _dispatch_main_queue_callback_4CF + 628
    15  CoreFoundation                      0x00000001126d9e39 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
    16  CoreFoundation                      0x000000011269e462 __CFRunLoopRun + 2402
    17  CoreFoundation                      0x000000011269d889 CFRunLoopRunSpecific + 409
    18  GraphicsServices                    0x0000000117eb99c6 GSEventRunModal + 62
    19  UIKit                               0x00000001139db5d6 UIApplicationMain + 159
    20  Geographical_Photo_Map              0x000000010f11b19f main + 111
    21  libdyld.dylib                       0x000000011363ed81 start + 1
)

I tried to debug, now seems that the exception happens in this place:

//NSURL *localFile = [NSURL URLWithString: path];
NSURL *localFile = path;

I tried both of them, both none of them seems to be working.

My full code:

// This method is called when an image has been chosen from the library or taken from the camera.
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    //You can retrieve the actual UIImage
    UIImage *image = [info valueForKey:UIImagePickerControllerOriginalImage];
    //Or you can get the image url from AssetsLibrary
    NSURL *path = [info valueForKey:UIImagePickerControllerReferenceURL];

    [picker dismissViewControllerAnimated:YES completion:nil];
    NSLog(@"finish choosing image.");
    NSLog(path);


    // Upload to firebase
    // Local file you want to upload
    //NSURL *localFile = [NSURL URLWithString: path];
    NSURL *localFile = path;

    // Create the file metadata
    FIRStorageMetadata *metadata = [[FIRStorageMetadata alloc] init];
    metadata.contentType = @"image/jpeg";

    // Get a reference to the storage service using the default Firebase App
    FIRStorage *storage = [FIRStorage storage];

    // Create a storage reference from our storage service
    FIRStorageReference *storageRef = [storage reference];

    // Upload file and metadata to the object 'images/mountains.jpg'
    FIRStorageUploadTask *uploadTask = [storageRef putFile:localFile metadata:metadata];


    // Listen for state changes, errors, and completion of the upload.
    [uploadTask observeStatus:FIRStorageTaskStatusResume handler:^(FIRStorageTaskSnapshot *snapshot) {
        // Upload resumed, also fires when the upload starts
    }];

    [uploadTask observeStatus:FIRStorageTaskStatusPause handler:^(FIRStorageTaskSnapshot *snapshot) {
        // Upload paused
    }];

    [uploadTask observeStatus:FIRStorageTaskStatusProgress handler:^(FIRStorageTaskSnapshot *snapshot) {
        // Upload reported progress
        double percentComplete = 100.0 * (snapshot.progress.completedUnitCount) / (snapshot.progress.totalUnitCount);
    }];

    [uploadTask observeStatus:FIRStorageTaskStatusSuccess handler:^(FIRStorageTaskSnapshot *snapshot) {
        // Upload completed successfully
    }];

    // Errors only occur in the "Failure" case
    [uploadTask observeStatus:FIRStorageTaskStatusFailure handler:^(FIRStorageTaskSnapshot *snapshot) {
        if (snapshot.error != nil) {
            switch (snapshot.error.code) {
                case FIRStorageErrorCodeObjectNotFound:
                    // File doesn't exist
                    break;

                case FIRStorageErrorCodeUnauthorized:
                    // User doesn't have permission to access file
                    break;

                case FIRStorageErrorCodeCancelled:
                    // User canceled the upload
                    break;

                case FIRStorageErrorCodeUnknown:
                    // Unknown error occurred, inspect the server response
                    break;
            }
        }
    }];

}

- (IBAction)UploadButtonClicked:(id)sender {
    // Choose from photo library.
    UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
    imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    imagePickerController.delegate = self;
    [self presentViewController:imagePickerController animated:YES completion:nil];
}

Seems like the error is about the format NSURL? But I think the parameters I used is NSURL? I will be greatly appreciated if someone offers any suggestions or solutions!

Answer 1

The stack trace has been clearly indicated which statement made your app crash:

0x000000011086c023 NSLog + 132

You have misused NSLog function as follow:

NSURL *path = [info valueForKey:UIImagePickerControllerReferenceURL];

[picker dismissViewControllerAnimated:YES completion:nil];
NSLog(@"finish choosing image.");
NSLog(path);    // <---- This statement make you crash

You can't directly pass a NSURL parameter to NSLog function, because NSLog is a C function. The prototype of NSLog is:

void NSLog(NSString *format, ...) NS_FORMAT_FUNCTION(1,2) NS_NO_TAIL_CALL

To fix this issue, you should call it as:

NSLog(@"URL: %@", path);

Answer 2

I am not sure why you're using NSURL to upload an image, but you can just use (I usually use) NSData generated directly from a UIImage, like so:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
    [picker dismissViewControllerAnimated:YES completion:nil];

    // Get the selected image.
    UIImage *image = [info valueForKey:UIImagePickerControllerEditedImage];

    // Generate a data from the image selected
    NSData *imageData = UIImageJPEGRepresentation(image, 0.8);

    // Create the file metadata
    FIRStorageMetadata *metadata = [[FIRStorageMetadata alloc] init];
    metadata.contentType = @"image/jpeg";

    // Get a reference to the storage service using the default Firebase App
    FIRStorage *storage = [FIRStorage storage];

    // Create a storage reference from our storage service
    FIRStorageReference *storageRef = [storage reference];

    // Upload file and metadata to the object 'images/mountains.jpg'
    FIRStorageUploadTask *uploadTask = [storageRef putData:imageData metadata:metadata];

    // Listen for state changes, errors, and completion of the upload.
    [uploadTask observeStatus:FIRStorageTaskStatusResume handler:^(FIRStorageTaskSnapshot *snapshot) {
        // Upload resumed, also fires when the upload starts
    }];

}

In this way (above), you get a change to lower the compression quality of your image before the upload.

Anyways, if you're going to generate a local path of your selected image from the picker, you can use check this out:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
    [picker dismissViewControllerAnimated:YES completion:nil];

    // Get the selected image's NSURL.

    NSURL *imagePath = [info objectForKey:@"UIImagePickerControllerReferenceURL"];
    NSString *imageName = [imagePath lastPathComponent];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *localFilePathString = [documentsDirectory stringByAppendingPathComponent:imageName];
    NSURL *localFile = [NSURL URLWithString:localFilePathString];

    // Create the file metadata
    FIRStorageMetadata *metadata = [[FIRStorageMetadata alloc] init];
    metadata.contentType = @"image/jpeg";

    // Get a reference to the storage service using the default Firebase App
    FIRStorage *storage = [FIRStorage storage];

    // Create a storage reference from our storage service
    FIRStorageReference *storageRef = [storage reference];

    // Upload file and metadata to the object 'images/mountains.jpg'
    FIRStorageUploadTask *uploadTask = [storageRef putFile:localFile metadata:metadata];

    // Listen for state changes, errors, and completion of the upload.
    [uploadTask observeStatus:FIRStorageTaskStatusResume handler:^(FIRStorageTaskSnapshot *snapshot) {
        // Upload resumed, also fires when the upload starts
    }];

}

So I bet that you are generating incorrectly the local path, hence the crash, you're giving a path that contains nil.

I hope this helps!