如何以编程方式在右上角创建信息按钮？

Question

我想这样做，但按钮不会显示：

// Create a Button to get Help   
UIButton *helpButton = [UIButton buttonWithType:UIButtonTypeInfoDark ] ; 
CGRect buttonRect = helpButton.frame; 

// Calculate the top right corner 
buttonRect.origin.x = self.tableView.frame.size.width - buttonRect.size.width - 8; 
buttonRect.origin.y = self.tableView.frame.size.height - buttonRect.size.height - 8; 
[helpButton setFrame:buttonRect]; 

[helpButton addTarget:self action:@selector(doHelp:) 
forControlEvents:UIControlEventTouchUpInside]; 
[helpButton setEnabled:TRUE]; 
[self.tableView addSubview:helpButton]; 

我究竟做错了什么？

UPDATE 修复代码是在这里的任何人有兴趣：

// Create a Button to get Help   
UIButton *helpButton = [UIButton buttonWithType:UIButtonTypeInfoDark ] ; 
CGRect buttonRect = helpButton.frame; 

// CALCulate the bottom right corner 
buttonRect.origin.x = self.view.frame.size.width - buttonRect.size.width - 8; 
buttonRect.origin.y = buttonRect.size.height - 8; 
[helpButton setFrame:buttonRect]; 

[helpButton addTarget:self action:@selector(doHelp:) forControlEvents:UIControlEventTouchUpInside]; 
[self.view addSubview:helpButton]; 

Answer 1

尝试将它添加到self.view不self.tableview