NSImage category for writing image to file

gistfile1.m

// [image writeToFile:[NSURL fileURLWithPath:@"/some/path/image.png"]];
- (void)writeToFile:(NSURL *)fileURL
{
  NSBitmapImageRep *bitmapRep = nil;
  
  for (NSImageRep *imageRep in [self representations])
  {
    if ([imageRep isKindOfClass:[NSBitmapImageRep class]])
    {
      bitmapRep = (NSBitmapImageRep *)imageRep;
      break; // stop on first bitmap rep we find
    }
  }
  
  if (!bitmapRep)
  {
    bitmapRep = [NSBitmapImageRep imageRepWithData:[self TIFFRepresentation]];
  }

  NSData *imageData = [bitmapRep representationUsingType:[self fileTypeForFile:[fileURL lastPathComponent]] properties:nil];
  [imageData writeToURL:fileURL atomically:NO];
}


- (NSBitmapImageFileType)fileTypeForFile:(NSString *)file
{
  NSString *extension = [[file pathExtension] lowercaseString];
  
  if ([extension isEqualToString:@"png"])
  {
    return NSPNGFileType;
  }
  else if ([extension isEqualToString:@"gif"])
  {
    return NSGIFFileType;
  }
  else if ([extension isEqualToString:@"jpg"] || [extension isEqualToString:@"jpeg"])
  {
    return NSJPEGFileType;
  }
  else
  {
    return NSTIFFFileType;
  }
}