You Can Have It In Any Color – As Long As It’s Black

I’ve been banging my head up against a wall today over something that should be easy.

What was I trying to do?

Well, I’ve been working this week on a new app for TweetPhoto.com that will allow you to post photos from your iPhone to the TweetPhoto web service.  In fact I wrote about it here.

I thought I had one problem licked – sending geo tag information to the API call.  As it turns out, I had only HALF the problem licked.

Initially, I was using the phone’s CoreLocation services to determine location and upload that to the API.  This is totally cool when you are using the camera.

Not so much when uploading photos taken elsewhere.  Ouch.

OK.  No problem.  I know the phone stores EXIF (exchangeable image file format) information with the JPEGS it takes, so it should be a slam dunk to grab that from th image picker control, right?

Wrong, grasshopper (with props to the recently deceased David Carradine).

The image picker STRIPS all EXIF information from photos passed in from the camera roll, so you, Mr. and / or Mrs. Developer, are screwed.

OK.  I’m a fart smeller.  I should be able to figure this out.

Hey – what if I can find where the camera roll is on the iPhone, enumerate it directly and read the image files from there?

Oh.  Heavenly Days.  That is a GREAT idea.

So, I trot out this gem, feeling like I have the problem close to being solved:

—

-(void)getCoords:(UIImage *)image lat:(float*)latAddr lon:(float*)lonAddr {

NSDirectoryEnumerator *enumerator  = [[NSFileManager defaultManager] enumeratorAtPath:  @”var/mobile/Media/DCIM/100APPLE”];
NSAutoreleasePool *innerPool = [[NSAutoreleasePool alloc] init];
id curObject;

*latAddr = 0;
*lonAddr = 0;

while ((curObject = [enumerator nextObject])) {
if ([[curObject pathExtension] isEqualToString:@”JPG”]) {

NSData * fileContents = [NSData dataWithContentsOfFile:[NSString stringWithFormat:@”var/mobile/Media/DCIM/100APPLE/%@”, curObject]];
UIImageView * seeMe = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
seeMe.image = [UIImage imageWithData:fileContents];

// First, we’ll get a JPEG representation of the image
EXFJpeg* jpegScanner = [[EXFJpeg alloc] init];
[jpegScanner scanImageData:fileContents];
EXFGPSLoc * lat    = [jpegScanner.exifMetaData tagValue:[NSNumber numberWithInt:EXIF_GPSLatitude]];
NSString * latRef = [jpegScanner.exifMetaData tagValue:[NSNumber numberWithInt:EXIF_GPSLatitudeRef]];
EXFGPSLoc * lon    = [jpegScanner.exifMetaData tagValue:[NSNumber numberWithInt:EXIF_GPSLongitude]];
NSString * lonRef = [jpegScanner.exifMetaData tagValue:[NSNumber numberWithInt:EXIF_GPSLongitudeRef]];

float flat = [[NSString stringWithFormat:@”%f”, lat.degrees.numerator + ((float)lat.minutes.numerator / (float)lat.minutes.denominator) / 60.0] floatValue];
float flon = [[NSString stringWithFormat:@”%f”, lon.degrees.numerator + ((float)lon.minutes.numerator / (float)lon.minutes.denominator) / 60.0] floatValue];

if ([[latRef substringToIndex:1] isEqualToString:@”S”]) {
flat = -flat;
}
if ([[lonRef substringToIndex:1] isEqualToString:@”W”]) {
flon = -flon;
}

// Does the image match???
if (seeMe == image) {
*latAddr = flat;
*lonAddr = flon;
return;
}

[jpegScanner release];
[seeMe release];
}

[innerPool release];
innerPool = [[NSAutoreleasePool alloc] init];
}
[innerPool release];
innerPool = nil;
}

NOW I’m rolling.  This works GREAT.  I can read images, extract EXIF information… feeling good.

Until I realize that I have NO way to associate the files that I am reading directly from what the image picker returns to me.  Did I just say “shit” out loud?  Because that is what I’m swimming in.

The image picker simply hands back an UIImage with some editing information.  That’s it.

OK, OK, OK.  Maybe I can compare NSData elements… or UIImage elements against what I read from disk and what the picker sends back… so far, neither of those approaches is working.

And now I’m sitting here, realizing that I can accurately describe ANY image’s geo tagging information.  I just can’t pick a SPECIFIC image from the bunch, well, at least using Apple’s APIs.

I’m coming to the sad realization that I might have to write my own bastardized version of the image picker, at least for scrolling through the camera roll.

I ain’t skeered to do it.  I just wish I didn’t have to.

But that looks like that’s exactly what I’m gonna have to do.  Damn it.

Posting Photos using Objective-C

Or more specifically, posting photos to tweetPhoto.com… but the method works for posting any image from an iPhone to any site that can accept POSTed images.

You can find the API documentation for tweetPhoto here.

Since using NSURLConnection and NSMutableRequest are covered numerous places elsewhere, I’m not going to describe much about how to make asynchronous HTTP calls.  The code below pretty much speaks for itself.

The interesting parts of this function (sendPhoto:tweet:photo:tags:longitude:latitude) are the portions involved in composing the HTTP form data to go over the wire.  Again, the code is fairly self explanatory.

The inbound (NSData*)photo should be the binary image of a picture that you will be sending to tweetPhoto (or whatever service you’re posting images to).  Please note that you will need to Change the Content-Type to match whatever images you’ll be sending (in my case, I always send .PNG images).

So, without further ado, here’s the deal-ee-oh:

-(void)sendPhoto:(NSString*)message tweet:(BOOL)tweet photo:(NSData*)photo tags:(NSString*)tags longitude:(float)longitude latitude:(float)latitude {
TweetPhotoAppDelegate* myApp = (TweetPhotoAppDelegate*)[[UIApplication sharedApplication] delegate];

NSString *url;
if (tweet) {
url = [NSString stringWithFormat:@"http://www.tweetphoto.com/uploadandpostapiwithkey.php"];
} else {
url = [NSString stringWithFormat:@"http://www.tweetphoto.com/uploadapiwithkey.php"];
}

NSString * boundary = @"tweetPhotoBoundaryParm";
NSMutableData *postData = [NSMutableData dataWithCapacity:[photo length] + 1024];

NSString * userNameString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"username\"\r\n\r\n%@", myApp.loginString];
NSString * passwordString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"password\"\r\n\r\n%@", myApp.passwordString];
NSString * apiString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"api_key\"\r\n\r\n%@", apiKey];
NSString * messageString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"message\"\r\n\r\n%@", message];
NSString * tagsString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"tags\"\r\n\r\n%@", tags];
NSString * latString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"latitude\"\r\n\r\n%f", latitude];
NSString * longString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"longitude\"\r\n\r\n%f", longitude];
NSString * boundaryString = [NSString stringWithFormat:@"\r\n--%@\r\n", boundary];
NSString * boundaryStringFinal = [NSString stringWithFormat:@"\r\n--%@--\r\n", boundary];

[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[userNameString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[passwordString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[apiString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];

if (message != nil && ![message isEqualToString:@""]) {
[postData appendData:[messageString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
}

if (tags != nil && ![tags isEqualToString:@""]) {
[postData appendData:[tagsString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
}

if (longitude && latitude) {
[postData appendData:[latString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[longString dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
}

[postData appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"media\";\r\nfilename=\"media.png\"\r\nContent-Type: image/png\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:photo];
[postData appendData:[boundaryStringFinal dataUsingEncoding:NSUTF8StringEncoding]];

NSMutableRequest * theRequest=(NSMutableURLRequest*)[NSMutableURLRequest requestWithURL:[NSURL URLWithString:url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];

[theRequest setHTTPMethod:@"POST"];

[theRequest addValue:[NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary] forHTTPHeaderField:@"Content-Type"];
[theRequest addValue:@"www.tweetphoto.com" forHTTPHeaderField:@"Host"];
NSString * dataLength = [NSString stringWithFormat:@"%d", [postData length]];
[theRequest addValue:dataLength forHTTPHeaderField:@"Content-Length"];
[theRequest setHTTPBody:(NSData*)postData];

NSURLConnection * theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
if (theConnection) {
receivedData=[[NSMutableData data] retain];
}
else {
[myApp addTextToLog:@"Could not connect to the network" withCaption:@"tweetPhoto"];
}
}