Post a UIImage to the web

So here is something a lot of people have been wondering to do in the forums. How do I take a UIImage or any image and post it to a website. So this will go over how to do that.

There are two ways to tackle this issue. One we can base64 encode the file and post is normally inside a XML or JSON instance or we can simulate a normal HTML post. This tutorial will go over the HTML post.

This will start off where Using a UIImagePickerController left off. So you can grab the code and start there if you want. So lets begin.

So first open up testPickerViewController.h and we want to add in one outlet and one action.

So here is the outlet we want to add

IBOutlet UIButton *upload;

Here is the action we want to add

IBOutlet UIButton *upload;

Now double click on testPickerViewController.xib and we need to connect the new outlet and action. We also need to create our new upload button. So drag around the current items and place the new button under the grab button. Then you want to make the button hidden by default. The option is as shown below. Do get to that selector you do Tools -> Attributes Inspector

You might also want to setup your UIImageView to aspect fit. If the image is larger then your box you created in IB it will shrink the image to fill it. Click on the UIImageView and in the Attributes Inspector select the following drop down for Mode

Now you want to make your connections to the new outlet and action we created in code. So here is another screenshot of what they should look like

Now it is back to the code. So save this and you can quit IB. 

So open up testPickerViewController.m_ _and find the imagePickerController method and at the end add 

upload.hidden = NO;

That will show our upload button once a image is set.

So now we need to create our uploadImage method that gets called then the button is pressed. So it is below and hopefully pretty well commented.

- (IBAction)uploadImage {
     turning the image into a NSData object
     getting the image back out of the UIImageView
     setting the quality to 90
    NSData *imageData = UIImageJPEGRepresentation(image.image, 90);
    // setting up the URL to post to
    NSString *urlString = @"";

    // setting up the request object now
    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
    [request setURL:[NSURL URLWithString:urlString]];
    [request setHTTPMethod:@"POST"];

     add some header info now
     we always need a boundary when we post a file
     also we need to set the content type

     You might want to generate a random boundary.. this is just the same 
     as my output from wireshark on a valid html post
    NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
    NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];
    [request addValue:contentType forHTTPHeaderField: @"Content-Type"];

     now lets create the body of the post
    NSMutableData *body = [NSMutableData data];
    [body appendData:[[NSString stringWithFormat:@"rn--%@rn",boundary] dataUsingEncoding:NSUTF8StringEncoding]];    
    [body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name="userfile"; filename="ipodfile.jpg"rn"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-streamrnrn"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[NSData dataWithData:imageData]];
    [body appendData:[[NSString stringWithFormat:@"rn--%@--rn",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    // setting the body of the post to the reqeust
    [request setHTTPBody:body];

    // now lets make the connection to the web
    NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];


So now if you build and go you will upload the image you selected to the following image URL

Below is my PHP file I am using to handle uploads.

$uploaddir = './uploads/';
$file = basename($_FILES['userfile']['name']);
$uploadfile = $uploaddir . $file;

if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {
        echo "{$file}";

It is nothing special. I do an echo so you can see in the console what the file is. If you switch the filename=”” part in the uploadImage section it will be placed as another file.

Files will be removed once they are 10 minutes old on the server so they won’t last but you can use it as a playground.

As always here is my [code][4].


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