Xcode If Statement not working properly

This isn't the whole code but I'm trying to get this to look to a textview box and see if a value has been put in. If not i won't it to do the first bit if not i want it to go to the else... however whatever i do it just crashes or doesn't work!!??

-(IBAction) sendPressed{

    if((youtubeurl.text = @"")){
        //if it doesnt have value
        NSLog(@"no youtube clip");
        youtubelink = @"";
    }
    else{
        //if youtube url has been entered
        NSLog(@"youtube clip found");
        completeurl = youtubeurl.text;
        youtubelink = [completeurl substringFromIndex:16];
    }