方法在iOS7中已经被Apple抛弃了，但还是可以用的
1 label.font = [UIFont fontWithName:@"Helvetica" size:20]; 2 CGSize size = [news_str sizeWithFont:label.font constrainedToSize:CGSizeMake(label.frame.size.width, MAXFLOAT) lineBreakMode:NSLineBreakByWordWrapping]; 3 label.frame = CGRectMake(label.frame.origin.x, label.frame.origin.y, size.width, size.height); 4 label.text = news_str;