如何在objective c中的单个视图控制器上加载多个UIView

UIView *firstView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
firstView.backgroundColor = [UIColor redColor];
firstView.layer.borderWidth = 1.0;
firstView.layer.borderColor = [UIColor blackColor].CGColor;
[self.view addSubview:firstView];

UIView *secondView = [[UIView alloc] initWithFrame:CGRectMake(120, 0, 100, 100)];
secondView.backgroundColor = [UIColor blueColor];
secondView.layer.borderWidth = 1.0;
secondView.layer.borderColor = [UIColor blackColor].CGColor;
[self.view addSubview:secondView];