IOS Label 自动换行 IOS6和IOS7

//计算实际frame大小，并将label的frame变成实际大小
    CGSize size01 = [ssizeWithFont:[UIFontsystemFontOfSize:15.0f]constrainedToSize:sizelineBreakMode:NSLineBreakByWordWrapping];

    [label setFrame:CGRectMake(10,50, size01.width, size01.height)];

 UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100, 46)];
    NSString *str=@"发恶无法奶奶问服务就啃发觉我看能否尽快稳罚款金额为你放假";
    label.text=str;
    UIFont *font=[UIFont systemFontOfSize:15];
    label.font=font;
    
    //拆行
    label.lineBreakMode=NSLineBreakByWordWrapping;
    //设置多行
    [label setNumberOfLines:0];
    
    //设置最大尺寸的宽和高
    CGSize size=CGSizeMake(100, 1000);
    //获取当前字体
    NSDictionary *dict=@{NSFontAttributeName: [UIFont systemFontOfSize:15]};
    CGSize authSize=[str boundingRectWithSize:size
                                       options:NSStringDrawingUsesLineFragmentOrigin
                                    attributes:dict
                                       context:nil].size;
    label.frame=CGRectMake(20, 70, authSize.width, authSize.height);
    [self.view addSubview:label];