iOS label显示富文本

NSString * htmlString = @" Some html string \nThis is some text!"; 
NSAttributedString * attrStr = [[NSAttributedString alloc] initWithData:[htmlString dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil]; 
UILabel * myLabel = [[UILabel alloc] initWithFrame:self.view.bounds];
 myLabel.attributedText = attrStr;
 [self.view addSubview:myLabel];