UILabel根据内容自动调整高度

    NSString *str = @"sagjojaisdhglahik阿斯顿能够";

    UIFont *font = [UIFont systemFontOfSize:14];

    CGSize size = CGSizeMake(320,2000);

    

    CGRect labelRect = [str boundingRectWithSize:size options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)  attributes:[NSDictionary dictionaryWithObject:font forKey:NSFontAttributeName] context:nil];

    

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0, 100, labelRect.size.width, labelRect.size.height)];

    label.text = str;

    label.numberOfLines = 0;

    label.backgroundColor = [UIColor blueColor];

    label.font = [UIFont systemFontOfSize:14];

    [self.view addSubview: label];