CGSize maximumSize = CGSizeMake(300, 9999);
    NSString *dateString = @"The date today is January 1st, 1999";
    UIFont *dateFont = [UIFont fontWithName:@"Helvetica" size:14];
    CGSize dateStringSize = [dateString sizeWithFont:dateFont 
        constrainedToSize:maximumSize 
        lineBreakMode:self.dateLabel.lineBreakMode];

    CGRect dateFrame = CGRectMake(10, 10, 300, dateStringSize.height);

    self.dateLabel.frame = dateFrame;

http://stackoverflow.com/questions/1054558/uilabel-vertical-alignment

UILabel Vertical Align

Objective C