iPhone how to send a large image along with a JSON file? Should I embed it within the JSON or send separately? - iphone

I'm trying to create a way to save the interface of my app in a JSON file. While static elements I can define by their frames and/or center points, the interface does include a single image selected from the photo library. Because some iPhones have 8MP cameras, I can anticipate that some images would be very large.
I would like to be able to save this interface and send it over by email, so another app user can re-open the file and see the same interface with the image included.
Currently I'm using JSONKit to save my data into a JSON object. This means that the email will contain a single JSON file containing both the layout parameters and the image. I've never worked with such large JSON files, so the question is - will having several megs of image data within JSON present parsing issues? Or should I select some other file container that would have : first part JSON file, second part raw image data and then separate that file into a JSON string and a raw data string?
This is what I'm using currently to get a JSON file. After adding NSData to JSON, the convert to json method returns nil
NSString* currentURL = webView.request.mainDocumentURL.absoluteString;
[dictionary setValue:currentURL forKey:#"webViewAddress"];
//this call correctly returns the json string
NSLog(#"%#", [dictionary JSONString]);
NSLog(#"+++++++++++++++++++++++++++++++++++++");
NSData* imageData = UIImagePNGRepresentation(arOverlayView.image);
//after this call, the json returns nil
[dictionary setValue:imageData forKey:kimageData];
NSLog(#"%#", [dictionary JSONString]);


If you are using email as a transport mechanism, your binary data will have to end up as something like Base64 encoded at some point in its life. There is no "raw" format for email, there is only text.
At best you could implement Base85 encoding which is more efficient than Base64
So you are going to have to suck up the large file sizes unless you invent your own transport mechanism - such as a point to point TCP/IP based link.

Related

Performance problem with saving images locally and writing to api in Swift 4

We are transforming images to a byte array and then saving them as a string in a JSON file. This happens locally on the file system. When reading this JSON file from the file system or writing it to the API the performance is really bad. For large quantities of images you have to wait >10 sec, before it is loaded in the ViewController. Is there a better way or library (Swift4) to deal with this? We are already compressing the quality to 0.2. Someone told us to use base64, is this the way to go?
We encode the image like this:ImagesBytes : [[UInt8]]? in to a JSON File with some TextField data.
This is the code
public var formImagesBytes : [[UInt8]]? = [] So this is in the model as a field. The model is a form with fields(strings) and an array of images which is an array of UInt8. This will be first saved locally while decoding it like this:
formImagesBytes = try container.decodeIfPresent([[UInt8]].self, forKey: .formImagesBytes)
Then we JSON encode all the data, including values of the form and image array of bytes. Then we add it with the Filemanager to the local storage on the device. We can open this file and it is including the formdata and an array of bytes in this case.
When loading the data from the local storage in the viewcontroller we again read this local file en decode it to a form model. But processing this file is taking too much time. I hope it is clear. My question is not really about the code, but about: is there a best practice or better way to write the image to this JSON file in order to let the app perform better.
Example output:
{"Images":[[255,216,255,224,0,16,74,70,73,70,0,1,1,0,0,144,0,144,0,0,255,225,0,140,69,120,105,102,0,0,77,77,0,42,0,0,0,8,0,5,1,18,0,3,0,0,0,1,0,1,0,0,1,26,0,5,0,0,0,1,0,0,0,74,1,27,0,5,0,0,0,1,0,0,0,82,1,40,0,3,0,0,0,1,0,2,0,0,135,105,0,4,0,0,0,1,0,0,0,90,0,0,0,0,0,0,0,144,0,0,0,1,0,0,0,144,0,0,0,1,0,3,160,1,0,3,0,0,0,1,0,1,0,0,160,2,0,4,0,0,0,1,0,0,1,82,160,3,0,4,0,0,0,1,0,0,0,253,0,0,0,0,255,237,0,56,80,104,111,116,111,115,104,111,112,32,51,46,48,0,56,66,73,77,4,4,0,0,0,0,0,0,56,66,73,77,4,37,0,0,0,0,0,16,212,29,140,217,143,0,178,4,233,128,9,152,236,248,66,126,255,192,0,17,8,0,253,1,82,3,1,34,0,2,17,1,3,17,1,255,196,0,31,0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0,0,1,2,3,4,5,6,7,8,9,10,11,255,196,0,181,16,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,125,1,2,3,0,4,17,5,18,33,49,65,6,19,81,97,7,34,113,20,50,129,145,161,8,35,66,177,193,21,82,209,240,36,51,98,114,130,9,10,22,23,24,25,26,37,38,39,40,41,42,52,53,54,55,56,57,58,67,68,69,70,71,72,73,74,83,84,85,86,87,88,89,90,99,100,101,102,103,104,105,106,115,116,117,118,119,120,121,122,131,132,133,134,135,136,137,138,146,147,148,149,150,151,152,153,154,162,163,164,165,166,167,168,169,170,178,179,180,181,182,183,184,185,186,194,195,196,197,198,199,200,201,202,210,211,212,213,214,215,216,217,218,225,226,227,228,229,230,231,232,233,234,241,242,243,244,245,246,247,248,249,250,255,196,0,31,1,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,1,2,3,4,5,6,7,8,9,10,11,255,196,0,181,17,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,119,0,1,2,3,17,4,5,33,49,6,18,65,81,7,97,113,19,34,50,129,8,20,66,145,161,177,193,9,35,51,82,240,21,98,114,209,10,22,36,52,225,37,241,23,24,25,26,38,39,40,41,42,53,54,55,56,57,58,67,68,69,70,71,72,73,74,83,84,85,86,87,88,89,90,99,100,101,102,103,104,105,106,115,116,117,118,119,120,121,122,130,131,132,133,134,135,136,137,138,146,147,148,149,150,151,152,153,154,162,163,164,165,166,167,168,169,170,178,179,180,181,182,183,184,185,186,194,195,196,197,198,199,200,201,202,210,211,212,213,214,215,216,217,218,226,227,228,229,230,231,232,233,234,242,243,244,245,246,247,248,249,250,255,219,0,67,0,28,28,28,28,28,28,48,28,28,48,68,48,48,48,68,92,68,68,68,68,92,116,92,92,92,92,92,116,140,116,116,116,116,116,116,140,140,140,140,140,140,140,140,168,168,168,168,168,168,196,196,196,196,196,220,220,220,220,220,220,220,220,220,220,255,219,0,67,1,34,36,36,56,52,56,96,52,52,96,230,156,128,156,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,230,255,221,0,4,0,22,255,218,0,12,3,1,0,2,17,3,17,0,63,0,223,162,138,40,16,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,1,255,208,223,162,138,40,16,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,1,255,209,223,162,138,40,16,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,1,255,210,223,162,138,40,16,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0,81,69,20,0]],
Here is a screenshot:
Output of the Image in a ByteArray

The JSON you posted explains why it is taking so long to parse. It probably takes a while to parse these huge arrays.
Instead of having each image as an array of bytes it should just be one base64 encoded string for each image. Something like this:
public var formImagesBase64 : [String]?
Here is some Swift code that might help you:
// Encoding Image
let data = image.jpegData(compressionQuality: 1)
let b64string = data?.base64EncodedString()
// Decoding image
let decodedData = Data(base64Encoded: b64string!)
let decodedImage = UIImage(data: decodedData!)

Converting a photo data to nsstring returns nil

I'm allowing the users of my app to either take a pic or select one from their library. When selected I need to get the images' data and convert it to a string so I can send it to a web service.
The problem I'm currently having is that [NSString initWithData:] is returning nil when I have the encoding set to UTF8. I need to set it to UTF8 for the XML message.
NSString *dataString = [[NSString alloc] initWithData:UIImageJPEGRepresentation(theImage, 1.0) encoding:NSUTF8StringEncoding];
Thanks for any advice!

You can't convert an UIImage to NSString by using initWithData:encoding: method. This method is only for converting an string's data to NSString (an Text File for example).
If you are trying to convert any kind of binary data to NSString, there are some kind of encoding available. Base64 is widely used. Also your server should have the ability to decode what you've sent.
In addition, in most cases, send an image to server just need to POST it in binary as it used to be.

NSData to NSString using initWithBytes:length:encoding

I have some image data (jpeg) I want to send from my iPhone app to my webservice. In order to do this, I'm using the NSData from the image and converting it into a string which will be placed in my JSON.
Currently, I'm doing this:
NSString *secondString = [[NSString alloc] initWithBytes:[result bytes]
length:[result length]
encoding:NSUTF8StringEncoding];
Where result is of type NSData. However, secondString appears to be null even though result length returns a real value (like 14189). I used this method since result is raw data and not null-terminated.
Am I doing something wrong? I've used this code in other areas and it seems to work fine (but those areas I'm currently using it involve text not image data).
TIA.

For binary data, better to encode it using Base64 encoding then decode it in you webservice. I use NSData+Base64 class downloaded from here, this reference was also taken from Stackoverflow, an answer made by #Ken (Thanks Ken!).

You are not converting the data to a string. You are attempting to interpret it as a UTF-8 encoded string, which will fail unless the data really is a UTF-8 encoded string. Your best bet is to encode it somehow, perhaps with Base64 as Manny suggests, and then decode it again on the server.

CoreData : store images to DB or not?

I am making an app that takes photos from web site for some Username and shows it in a UITable with username then when clicking user name it shows photos for this user and then clicking to name of photo it shows full screen photo.
My question is I am using NSData to get photos from internet. Do I have to save the data to CoreData? When pressing name of user it creates NSData and downloads photos from internet and shows them on UITable. And it takes time.
What is good approach? and How can save this images to CoreData?
I am using this method
NSData *imageData=[flickr dataForPhotoID:firstPhoto.id fromFarm:firstPhoto.farm
onServer:firstPhoto.server withSecret:firstPhoto.secret inFormat:
FlickrFetcherPhotoFormatSquare];
and here definition of dataForPhotoID method
- (NSData *)dataForPhotoID:(NSString *)photoID fromFarm:(NSString *)farm
onServer:(NSString *)server withSecret:(NSString *)secret
inFormat:(FlickrFetcherPhotoFormat)format {
#if TEST_HIGH_NETWORK_LATENCY
sleep(1);
#endif
NSString *formatString;
switch (format) {
case FlickrFetcherPhotoFormatSquare: formatString = #"s"; break;
case FlickrFetcherPhotoFormatLarge: formatString = #"b"; break;
}
NSString *photoURLString = [NSString stringWithFormat:#"http://farm%#.static.flickr.com/%#/%#_%#_%#.jpg", farm, server, photoID, secret, formatString];
NSURL *url = [NSURL URLWithString:photoURLString];
return [NSData dataWithContentsOfURL:url];
}

First, always store your images in a usable format such as PNG or JPEG instead of NSData. This will save you a lot of headaches.
Second, the rule for storing binary data is:
< 100kb store in the same table as the relevant data
< 1mb store in a separate table attached via a relationship to avoid loading unnecessarily
1mb store on disk and reference it inside of Core Data
Update
The storage inside of Core Data should be binary and you can write accessor methods for it. Take a look at this answer: Core data images from desktop to iphone
Update
The example code I linked to describes how to create accessors in your NSManagedObject subclass that will convert the image back and forth between a UIImage and binary data.

You can simply store UIImage objects in CoreData directly, just use Transformable data type, and you are ready to go

Convert NSData [UIImage] to a NSString

I am aware this question has been asked several times, but I was unable to find a definate answer that would best fit my situation.
I want the ability to have the user select an image from the library, and then that image is converted to an NSData type. I then have a requirement to call a .NET C# webservice via a HTTP get so ideally I need the resulting string to be UTF8 encoded.
This is what I have so far:
NSData *dataObj = UIImageJPEGRepresentation(selectedImage, 1.0);
[picker dismissModalViewControllerAnimated:YES];
NSString *content = [[NSString alloc] initWithData:dataObj encoding:NSUTF8StringEncoding];
NSLog(#"%#", content);
The NSLog statement simply produces output as:
2009-11-29 14:13:33.937 TestUpload2[5735:207] (null)
Obviously this isnt what I hoped to achieve, so any help would be great.
Kind Regards

You can't create a UTF-8 encoded string out of just any arbitrary binary data - the data needs to actually be UTF-8 encoded, and the data for your JPEG image obviously is not. Your binary data doesn't represent a string, so you can't directly create a string from it - -[NSString initWithData:encoding:] fails appropriately in your case.
Assuming you're using NSURLConnection (although a similar statement should be true for other methods), you'll construct your NSMutableURLRequest and use -setHTTPBody: which you need to pass an NSData object to. I don't understand why you would be using a GET method here since it sounds like you're going to be uploading this image data to your web service - you should be using POST.