Titanium JIRA Archive
Titanium SDK/CLI (TIMOB)

[TIMOB-1611] iOS: base64 encoding/decoding of Blob cannot be round-tripped successfully

GitHub Issuen/a
Resolution Date2011-12-29T18:32:32.000+0000
Affected Version/sRelease 1.7.2
Fix Version/sRelease 1.8.0
Labelsblob, defect, ios, parity
ReporterThomas Huelbert
AssigneeStephen Tramer


This was already addressed for android as lighthouse ticket #1604, below are Bill's original notes from the bug.

You cannot use Titanium.Utils.base64encode & Titanium.Utils.base64decode successfully to round-trip the encoding / decoding of a blob. In other words, you don't get back the same set of bytes that you originally started with.

Failcase app.js (make sure you have KS_nav_ui.png in your Resources folder; it's there by default with new projects):

var win = Ti.UI.createWindow({fullscreen: true, exitOnClose:true});

var file = Ti.Filesystem.getFile('KS_nav_ui.png');

var blob1 = file.read();
var base64 = Ti.Utils.base64encode(blob1);
var blob2 = Ti.Utils.base64decode(base64);

var thumbnail1 = Titanium.UI.createView({left: 0, top: 0, width: 46, height: 43});
thumbnail1.backgroundImage = 'KS_nav_ui.png'; // the orig, which obviously works
var thumbnail2 = Titanium.UI.createView({left: 56, top: 0, width: 46, height: 43});
var thumbnail3 = Titanium.UI.createView({left: 112, top: 0, width: 46, height: 43});
win.add(thumbnail1); win.add(thumbnail2); win.add(thumbnail3);

var tempDir = Titanium.Filesystem.createTempDirectory();

// Blob from original file var file1 = Titanium.Filesystem.getFile(tempDir.nativePath, 'file1.png');
thumbnail2.backgroundImage = file1.nativePath;

// Base64 encoded-then-decoded blob var file2 = Titanium.Filesystem.getFile(tempDir.nativePath, 'file2.png');
thumbnail3.backgroundImage = file2.nativePath;

You should see three identical images when that runs. Instead, you'll see only two.


  1. James David Low 2011-04-15

    Hi, I'm an end user of Titanium that had some trouble with this recently.

    The problem on iPhone is that the TiBlob is converted to a String first using UtilsModule.convertToString grabbing the TiBlob.text field. If the TiBlob is an image or file you need to use the TiBlob.data field.

    I managed to get it to work using the attached code. I figured it was better to use the TiBlob.data rather than TiBlob.text always, as if you really must base64 encode a String from a blob you can change your Javascript to Ti.Utils.base64encode(blob.text) and it will still encode it.

    -(TiBlob*)base64encode:(id)args {

       const char *data;
       size_t len;
       if ([args isKindOfClass:[NSString class]])
           data = [args UTF8String];
           len = [args length];
       else if ([args isKindOfClass:[TiBlob class]])
           data = [[(TiBlob*)args data] bytes];
           len = [[(TiBlob*)args data] length];
           THROW_INVALID_ARG(@"invalid type");
       size_t outsize = EstimateBas64EncodedDataSize(len);
       char *base64Result = malloc(sizeof(char)*outsize);
       size_t theResultLength = outsize;
       bool result = Base64EncodeData(data, len, base64Result, &theResultLength);
       if (result)
           NSData *theData = [NSData dataWithBytes:base64Result length:theResultLength];
           return [[[TiBlob alloc] initWithData:theData mimetype:@"application/octet-stream"] autorelease];
       return nil;


  2. James David Low 2011-04-15

    I also created this function because I wanted the TiBlob I created to be an Image with width/height attributes. Is it possible to
    1) Add it to UtilsModule.m
    2) Have an optional parameter that determines the type of TiBlob to return
    3) Maybe even better have an TiBlob be able to create another TiBlob of type TiBlobTypeImage from the data within it. Maybe at the same time you could provide a constructor in Javascript to let us create our own TiBlobs from our own data.

    -(TiBlob*)base64decodeImage:(id)args {

       NSString *str = [self convertToString:args];
       const char *data = [str UTF8String];
       size_t len = [str length];
       size_t outsize = EstimateBas64DecodedDataSize(len);
       char *base64Result = malloc(sizeof(char)*outsize);
       size_t theResultLength = outsize;
       bool result = Base64DecodeData(data, len, base64Result, &theResultLength);
       if (result)
           NSData *theData = [NSData dataWithBytes:base64Result length:theResultLength];
           return [[[TiBlob alloc] initWithImage:[UIImage imageWithData:theData]] autorelease];
       return nil;


  3. James David Low 2011-10-14

    Hi Reggie, This problem isn't trivial its actually quite serious that it isn't able to do the round trip and makes it a bit unusable. I have a fully changed UtilsModule.m that has all the necessary changes: 1) To make a round trip possible 2) To return a image type TiBlob which has dimensions initiated. Please contact me about this, I'd really like to get it sorted as I have to make changes to the Titanium SDK every time there's an issue. You can use my email james.low @ onoko.com Thanks, James
  4. Wilson Luu 2011-11-01

    Bug is not valid, does not reproduce in: TiMOB sdk version: 1.8.0.v20111031173855 Studio version: OS version: Mac OS X Lion Devices tested on: ipad 4.3.5 Note: 1.7.2 still show this bug, 1.8.0.v20111031173855 fixes this bug
  5. Reggie Seagraves 2011-11-02

    Parity check with Android implementation.
  6. Stephen Tramer 2011-12-29

    Duplicate of TIMOB-6280.
  7. Lee Morris 2017-03-24

    Closing ticket as duplicate with reference to the linked issues.

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