iOS UILabel根据内容自动调整高度

- (void)viewDidLoad{ [super viewDidLoad]; // Do any additional setup after loading the view.  //根据内容自动调整高度 NSString *str = @"公元前3000年，印度河流域的居民的数字使用就已经比较普遍，居民们采用了十进位制的计算法。"; UIFont *font = [UIFont systemFontOfSize:13]; CGSize size = CGSizeMake(200,2000); CGRect labelRect = [str boundingRectWithSize:size options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading) attributes:[NSDictionary dictionaryWithObject:font forKey:NSFontAttributeName] context:nil];  //UILabel UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(50,100, labelRect.size.width, labelRect.size.height)]; label.text = str; label.backgroundColor=[UIColor redColor]; label.font = [UIFont systemFontOfSize:13]; label.numberOfLines=0; [self.view addSubview: label];}