根据当前字符串获取适合的宽高

//根据当前字符串获取适合的宽高 
- (CGSize)sizeWithText:(NSString *)text font:(UIFont *)font maxSize:(CGSize)maxSize {
    NSDictionary *fontDic = @{NSFontAttributeName:font};
    CGSize size;
    //返回当前字符串合适宽高信息
    size = [text boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:fontDic context:nil].size;
    return size;
}