自定义视图调用时，UIButton不可点击

我是iPhone开发的新手，我需要帮助来理解以下内容，因为我能够使用以下内容创建newView

I am new to iPhone development,I need help in understanding the below,as I am able to create newView using the following

UIView *newView=[[UIView alloc]initWithFrame:CGRectMake(0, 0, 80, 30)]; 
newView.backgroundColor=[UIColor clearColor];
UIButton *newViewBtn=[UIButton buttonWithType:UIButtonTypeRoundedRect];


newViewBtn.frame = CGRectMake(newView.frame.origin.x+5,
                            newView.frame.origin.y+5,60,20);
[newView addSubview:newViewBtn];
[self.view addSubview:newView]; 

以上代码可以正常工作.但是，当我尝试使用以下方法创建视图时，可以创建视图，但是视图上的按钮不可单击.

Above code is working without any problem. But when I try to create the view using the following, view is created alright, but the button on the view is not clickable.

int randNumX = arc4random() % 150;
int randNumY = arc4random() % 200;
UIView newView=[[UIView alloc]init];
newView.frame =CGRectMake(randNumX, randNumY, 80, 30);

newView.backgroundColor=[UIColor clearColor];

UIButton *newViewBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
newViewBtn.frame  = CGRectMake(newView.frame.origin.x+5
                         ,newView.frame.origin.y+5,60,20);
[newView addSubview:newViewBtn];
[self.view addSubview:newView];

如果更改以下代码，则还有另一种情况

and there is one another scenario if change the following code

 newViewBtn.frame = CGRectMake(newView.frame.origin.x+5
                          ,newView.frame.origin.y+5,60,20);

应用下面的代码崩溃

 newViewBtn.frame =CGRectMake(randNumX+5,randNumY+5,60,20);

任何帮助将不胜感激，谢谢.

Any help will be greatly appreciated,thanks in advance.

我已经添加了以下代码

     newViewBtn addTarget:self action:@selector(btnclick:)forControlEvents:UIControlEventTouchUpInside];

     -(void)btnclick:(id)sender
     {
       //my code
     }

在第一种情况下有效:

我在这里主要担心的是绘制newView时，为什么该视图上的按钮不可单击

My main concern here is when the newView is draw ,why the button on this view is not clickable