label高度根据字体大小适应

/**
 通过文字计算

 @param str 文本
 @param witdth 限制最大的宽度
 @param textFont 文本的font
 @return 返回的size
 */
- (CGSize)boundingRectWithStr:(NSString *)str width:(CGFloat )witdth Font:(CGFloat )textFont
{
    NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:textFont]};
    CGSize size = [str boundingRectWithSize:CGSizeMake(witdth, 0) options: NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:attribute context:nil].size;
    
    return size;
}