ios之UILabel实现文本自适应方法

- (void)initUserInterface
{
  UILabel *label = [[UILabel alloc]init];
  label.numberOfLines = 0; // 需要把显示行数设置成无限制
  label.font = [UIFont systemFontOfSize:15];
  label.textAlignment = NSTextAlignmentCenter;
  label.text = @"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
  CGSize size =  [self sizeWithString:label.text font:label.font];
  label.bounds = CGRectMake(0, 0, size.width, size.height);
  label.center = self.view.center;
  [self.view addSubview:label];
  
}
// 定义成方法方便多个label调用 增加代码的复用性
- (CGSize)sizeWithString:(NSString *)string font:(UIFont *)font
{
  CGRect rect = [string boundingRectWithSize:CGSizeMake(320, 8000)//限制最大的宽度和高度
                     options:NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesFontLeading  |NSStringDrawingUsesLineFragmentOrigin//采用换行模式
                  attributes:@{NSFontAttributeName: font}//传人的字体字典
                     context:nil];
  
  return rect.size;
}