ios8 中改变label的高度

iOS

    _titleLabel.numberOfLines = 0;
    _titleLabel.lineBreakMode = NSLineBreakByWordWrapping;
    NSLog(@"%f",_titleLabel.frame.size.height);
    CGSize size = [_titleLabel sizeThatFits:CGSizeMake(_titleLabel.frame.size.width, MAXFLOAT)];
    _titleLabel.frame = CGRectMake(_titleLabel.frame.origin.x, _titleLabel.frame.origin.y, _titleLabel.frame.size.width, size.height);
    if (size.height>20.5) {
        height =75+24;
        _headView.frame = CGRectMake(0, 64, Screen_W,height);
    }else{
        height =75;
        _headView.frame = CGRectMake(0, 64, Screen_W,height);
    }