Question

I am using UIImagePickerController in an iOS app to save an image in context using UIGraphicsBeginImageContext/UIGraphicsBeginImageContextWithOptions.

I recently noticed that I picture I had saved and then displayed at a later date was highly pixelated; when I went back with the same code and imported the photo again, I got a great image. After playing with this for a while on my device, I figured out that the quality of the image saved depends on WHEN I pressed the ‘Choose’ button on the ‘Move and Scale’ screen.

If the image is a larger image and still loading when I press the button, the image is pixelated… if I wait until the image loads, it is fine. My question is, is there any way I can control when the user presses the ‘Choose’ button – is there any way to force them to wait until after the image is fully loaded? Or is there another way that would be better to approach this issue?

- (void)choosePhoto {

    //NSLog(@"%s", __FUNCTION__);
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.allowsEditing = YES;

    imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    [self presentModalViewController:imagePicker animated:YES];
    [imagePicker release];
}

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

    //NSLog(@"%s", __FUNCTION__);
    [self dismissModalViewControllerAnimated:YES];

    UIImage *pickedImage = (UIImage*)[info objectForKey:@"UIImagePickerControllerEditedImage"];
    [self setPersonImage:pickedImage];
}


- (void) setPersonImage:(UIImage *)pickedImage  {

    //NSLog(@"%s", __FUNCTION__);

    NSManagedObjectContext *context = [[UIApplication sharedDelegate] managedObjectContext];
    PersonImage *oldImage = person.image;
    if (oldImage != nil) {
        [context deleteObject:(NSManagedObject*)oldImage];
    }

    if (pickedImage != nil) {
        // Create an image object for the new image.
        PersonImage *newImageObject = [NSEntityDescription insertNewObjectForEntityForName:@"PersonImage" inManagedObjectContext:context];
        [newImageObject setImage:pickedImage]; 
        [person setImage:newImageObject]; 
    }
    else {
        [person setImage:nil];
    }

    NSError *error;
    if (![context save:&error]) {
        exit(-1);  // Fail
    }
}

Answer 1

I suggest you implement your own Crop&Resize view controller.

1. set imagePicker.allowsEditing = NO.
2. create your view controller in - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info and pass selected image to your view controller.
3. push your view controller to image picker: [picker pushViewController:yourVC animated:YES]