- (void)viewDidLoad

{

    [super viewDidLoad];

    // Do any additional setup after loading the view.

    //把<br!>换成\n

    NSString *string=@"123<br!>456<br!>789";

    NSString *newStr=[string stringByReplacingOccurrencesOfString:@"<br!>" withString:@"\n"];

    NSString *newNewStr=[newStr stringByReplacingOccurrencesOfString:@"\n" withString:@"<br!>"];

    UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(10, 100, 100, 200)];

    label.backgroundColor=[UIColor redColor];

    label.text=newNewStr;

    //下面这个代码很重要，很重要的

    label.numberOfLines=0;

    [self.view addSubview:label];

}