UILabel自动换行及高度自适应

#pragma mark -- UILabel 自动换行 及 高度自适应

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 100, 200, 50)];

    label.text = @"      今天下午全市多云到阴有阵雨或雷雨由于爱情来得不容易";

    //清空背景颜色

    label.backgroundColor = [UIColor clearColor];

    //设置字体颜色为白色

    label.textColor = [UIColor whiteColor];

    //设置label的背景色为黑色

    label.backgroundColor = [UIColor cyanColor];

    //文字居中显示

    label.textAlignment = NSTextAlignmentLeft;

    //自动折行设置

    label.lineBreakMode = NSLineBreakByWordWrapping;

    label.numberOfLines = 0;

    //自适应高度

    CGRect txtFrame = label.frame;

    NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:label.font,NSFontAttributeName, nil];

    CGSize size = CGSizeMake(txtFrame.size.width, CGFLOAT_MAX);

    txtFrame.size.height =[label.text boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading

                                                attributes:attributes context:nil].size.height;

    label.frame = CGRectMake(10, 100, 200, txtFrame.size.height);

    [self.view addSubview:label];