How to send UIImage in JSON format, by filling a NSDictionary

Question

I'm trying to send data to a server with JSON. I am able to create my NSDictionary with my objects and key parameters. But I want to send my picture, and the picture is UIImage.

 NSDictionary* mainJSON = [NSDictionary dictionaryWithObjectsAndKeys:
                          @"John",
                          @"First_Name",
                          @"McCintosh",
                          @"Last_name",
                          <HERE I WANT PICTURE>,
                          @"Profile_picture",
                          nil];

 // Here I convert to NSDATA 
 NSData * jsonData = [NSJSONSerialization dataWithJSONObject:mainJSON options:NSJSONWritingPrettyPrinted error:&error];

 // Sending operation :
 dispatch_async(kBgQueue, ^
                   {
                       NSData * data = [NSData dataWithContentsOfURL:@"addresSERVER"];
                       [self performSelectorOnMainThread:@selector(receivedResponseFromServer:)
                                              withObject:data
                                           waitUntilDone:YES];
                   }
                   );

So I'm wondering how can I add my picture in my NSDictionary? Because I want to send the content of my picture. If I add my object UIImage... I'll send the whole object right?

Thanks

Answer 1

You should convert the UIImage to NSString. Use the category of NSData called NSDataAdditions.You can find here: NSDataAdditions category

How to Use:

//Convert an Image to String
UIImage *anImage;
NSString imageString = [UIImagePNGRepresentation(anImage) base64Encoding];

//To retrieve
NSData *data = [NSData dataWithBase64EncodedString:imageString];
UIImage *recoverImage = [[UIImage imageWithData:data];

Answer 2

I wouldn't typically post an image using JSON. Although it is technically possible to encode an image into text, I don't think that's how JSON is intended to be used and I would personally avoid the practice.

Deal with images as NSData. That's what they are. There are tons of examples online that illustrate how to do this.

One common approach is to upload an image to a web server, then take the URL of the uploaded image and add that to your JSON dictionary, such that your submitted JSON dictionary carries a string representing the URL of the image to download -- not the image itself.

Answer 3

You can try send UIImage with NSString like this: Swift 3:

if let jpegData = UIImageJPEGRepresentation(image, 1.0) {
    var encodedString = jpegData.base64EncodedString()
    var mainJSON = [
        "First_Name" : "John",
        "Last_name" : "McCintosh",
        "Profile_picture" : encodedString
    ]

}

Objective-c:

NSData *imageData = UIImageJPEGRepresentation(image, 1.0);
NSString *encodedString = [imageData base64Encoding];


 NSDictionary* mainJSON = [NSDictionary dictionaryWithObjectsAndKeys:
                          @"John",
                          @"First_Name",
                          @"McCintosh",
                          @"Last_name",
                          encodedString,
                          @"Profile_picture",
                          nil];

This is Base64 format so you can decode this in any language

Answer 4

Okay, Thansk to @tolgamorf and @isaac, I tried using AFNetwork. I could do what I want. It's powerful and simple.

NSURL *url = [NSURL URLWithString:@"http://api-base-url.com"];
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];
NSData *imageData = UIImageJPEGRepresentation([UIImage imageNamed:@"avatar.jpg"], 0.5);
NSMutableURLRequest *request = [httpClient multipartFormRequestWithMethod:@"POST"  path:@"/upload" parameters:nil constructingBodyWithBlock: ^(id <AFMultipartFormData>formData) {
[formData appendPartWithFileData:imageData name:@"avatar" fileName:@"avatar.jpg"  mimeType:@"image/jpeg"];
}];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[operation setUploadProgressBlock:^(NSUInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite) {
NSLog(@"Sent %lld of %lld bytes", totalBytesWritten, totalBytesExpectedToWrite);
}];
[httpClient enqueueHTTPRequestOperation:operation];

I took the code from official documentation from here .

Enjoy