UILabel基本用法

 UILabel *_label = [[UILabel alloc]initWithFrame:CGRectMake(,  self.view.frame.size.height*0.5f, self.view.frame.size.width*0.5f, )];
 _label.backgroundColor = [UIColor colorWithRed: green: blue: alpha:0.6];
 _label.textColor = [UIColor whiteColor];
 _label.layer.cornerRadius = ;
 _label.layer.masksToBounds= YES;
 _label .font = [UIFont systemFontOfSize:];
 _label .numberOfLines = ;
 _label .textAlignment = UITextAlignmentCenter;
 _label.text = @"轻触";
 [self.view addSubview:_label];