A QTMovie isn't writing to file

Question

I'm trying to add these images to the QTMovie, but the file never appears. I think it has something to do with the attributes or addImage:

NSTimeInterval t;
QTGetTimeInterval(frameInterval, &t);
NSLog(@"%f", t); // outputs 0.0333333


// --- initializes the movie ---
NSError *error = nil;

NSDictionary *at = [NSDictionary dictionaryWithObjectsAndKeys:
                    [NSNumber numberWithBool:YES], QTMovieEditableAttribute,
                    nil];

QTMovie *tst = [QTMovie movieWithAttributes:at error:&error];

if (error) {
    NSLog(@"%@", [error localizedDescription]); // outputs (null)
}


// --- initializes the images ---
NSImage *i1 = [[NSImage alloc] 
               initWithContentsOfFile:@"~/agimgs/1.tiff"];
NSImage *i2 = [[NSImage alloc] 
               initWithContentsOfFile:@"~/agimgs/110.tiff"];
NSImage *i3 = [[NSImage alloc] 
               initWithContentsOfFile:@"~/agimgs/130.tiff"];

// --- adds the images ---
for (int j=0; j<50; j++) {
    [tst addImage:i1 forDuration:frameInterval withAttributes:dict];
    [tst addImage:i2 forDuration:frameInterval withAttributes:dict];
    [tst addImage:i3 forDuration:frameInterval withAttributes:dict];
}

// --- (supposed to) output the movie ---
dict = [NSDictionary dictionaryWithObjectsAndKeys:
        [NSNumber numberWithBool:YES], QTMovieExport,
        nil];

BOOL worked = [tst writeToFile:@"/Users/nathanmswan/aaaa.mov" withAttributes:dict error:&error];
if (!worked) {
    NSLog(@"%@", [error localizedDescription]); // outputs nothing
}

NSLog(@"done with aaaa.mov");

Answer 1

You can write the movie directly to a file like this

NSString *tempName =  [NSString stringWithFormat:@"/Users/nathanmswan/aaaa.mov"];
tst = [[QTMovie alloc] initToWritableFile:tempName error:NULL];

after you have added a frame

[tst updateMovieFile];

This will create the file then write everything to the file, then save it. The writeToFile: will not be necessary. However, the 'dict' used in the addImage: method does not appear to be initialised before use...it should refer to the codec for addImage: For example,

dict = [NSDictionary dictionaryWithObjectsAndKeys:@"mp4v",
           QTAddImageCodecType,
           [NSNumber numberWithLong:codecHighQuality],
           QTAddImageCodecQuality,
           nil];