Can't get resized image to save at new size - objective-c

Question

I have the following code
if (! [url getResourceValue:&isDirectory forKey:NSURLIsDirectoryKey error:&error]) {
// handle error
}
else if (! [isValidDirectory boolValue]) {
// No error and it’s not a directory; do something with the file
NSString* outP = [url absoluteString];
NSString* extension = [outP substringFromIndex: outP.length-3];
NSString* img = #"png";
if([extension isEqualToString:img]){
NSImage *original = [[NSImage alloc] initWithContentsOfURL: url];
NSSize sizes = NSMakeSize(240, 240);
NSImage *small =original;
[small setSize:sizes];
NSArray* representations = [small representations];
NSInteger* total = [substrings count];
NSData* bitmapData = [NSBitmapImageRep representationOfImageRepsInArray: representations usingType: NSPNGFileType properties:nil];
[bitmapData writeToFile:#"/Users/testuser/downloads/test/test_tn.png" atomically:NO];
}
when I run it it does not resize the image it just gives me a straight copy of the image with the name test_tn.png instead of a smaller image. I'm not sure what I'm doing wrong, this is a mac app also. There is some unused code in there that is for later. Is the problem how I'm passing the NSImage to the NSData after i resize?
edit: ok so i converted the NSData back into an NSImage and it appears the NSData is not getting the sized data but the original data.
edit 2: so this works
ok so this works
if([extension isEqualToString:img]){
NSImage *image = [[NSImage alloc] initWithContentsOfURL: url];
NSData *sourcedata =[image TIFFRepresentation];
NSSize newSize;
newSize.height = 160;
newSize.width = 120;
NSImage *sourceImage =[[NSImage alloc] initWithData: sourcedata];
NSImage *resizedImage = [[NSImage alloc] initWithSize: NSMakeSize(240, 240)];
NSSize originalSize = [sourceImage size];
[resizedImage lockFocus];
[sourceImage drawInRect: NSMakeRect(0, 0, 240, 240) fromRect: NSMakeRect(0, 0, originalSize.width, originalSize.height) operation: NSCompositeSourceOver fraction: 1.0];
[resizedImage unlockFocus];
NSData *resizedData = [resizedImage TIFFRepresentation];
NSData *resizedPreviewData = [resizedImage TIFFRepresentation];
NSBitmapImageRep *resizedCaptureImageBitmapRep = [[NSBitmapImageRep alloc] initWithData:resizedPreviewData];
NSData* saveData = [resizedCaptureImageBitmapRep representationUsingType:NSPNGFileType properties:nil];
[saveData writeToFile:#"/Users/testuser/downloads/test/test_tn.png" atomically:YES];
count++;
}

Answer 1

This works for me. I am using this code to layer images on top of each other, but it should be easily adapted to your purposes:
CGSize destinationSize = smallSize;
UIGraphicsBeginImageContext(original.size);
[Original1 drawInRect:CGRectMake(0, 0, original.size.width, original.size.height)];
[Original2 drawInRect:CGRectMake(0, 0, original.size.width, original.size.height)];
UIImage *returnImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIGraphicsBeginImageContext(destinationSize);
[returnImage drawInRect:CGRectMake(0,0,destinationSize.width,destinationSize.height)];
UIImage *smallImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();