objective-c - 如何在 Cocoa 中显示和管理简单的应用程序模式对话框

Question

我不确定我做事的方式是否正确，或者我是否把一切都搞砸了。

我创建了一个非常简单的测试应用程序(不是基于文档的)，用于学习如何在 Cocoa 应用程序中使用应用程序模式对话框。

对于应用程序项目“TestModalDialog”，我有一个简单的 MainMenu.xib，带有默认 View 和一个按钮，“显示对话框”，我添加了。我创建了第二个名为 TheDialog.xib 的 XIB，它具有“取消”和“确定”按钮。 xib 拥有一个从 NSWindowController 派生的名为“TheDialogController”的类；窗口导出和委托(delegate)连接到 Controller 。

在主视图上选择“显示对话框”将启动对话框。选择“取消”或“确定”将关闭对话框。这是非常简单的代码:

//  TestModalDialogAppDelegate.h  
//  TestModalDialog  

#import <Cocoa/Cocoa.h>  

@class TheDialogController;  

@interface TestModalDialogAppDelegate : NSObject <NSApplicationDelegate>  
{  
  NSWindow *window;  
  TheDialogController* theDialogController;  
}  

@property (assign) IBOutlet NSWindow *window;  
- (IBAction)showDialog:(id)sender;  

@end  

//  TestModalDialogAppDelegate.m  
//  TestModalDialog  

#import "TestModalDialogAppDelegate.h"  
#import "TheDialogController.h"  

@implementation TestModalDialogAppDelegate  

@synthesize window;  

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification  
{  
  theDialogController= [[TheDialogController alloc] init];  
}  

- (void)dealloc  
{
  if(nil != theDialogController)   
    [theDialogController release];  

  [super dealloc];  
}  

- (IBAction)showDialog:(id)sender  
{  
  if(nil == theDialogController)  
  {  
    NSAlert* alert= [NSAlert alertWithMessageText:@"Dialog Error" defaultButton:nil alternateButton:nil otherButton:nil informativeTextWithFormat:@"The dialog controller was not allocated."];  
    [alert runModal];  
    return;  
  }

  NSInteger result= [NSApp runModalForWindow:[theDialogController window]]; 
  // Do something with result.... 
}  
@end  

//  TheDialogController.h  
//  TestModalDialog  

#import <Cocoa/Cocoa.h>  

@interface TheDialogController : NSWindowController  
{  
  // BOOL userClickedCloseOrOk; // Removed based on answer.  
  // Should declare a common define - just being lazy.  
  NSInteger userClickedOk;  // Added based on answer.  
  UInt16 timesShown;   
}  

- (IBAction)showWindow:(id)sender;  
- (IBAction)closeDialog:(id)sender;  
- (IBAction)okDialog:(id)sender;  
//- (BOOL)windowShouldClose:(id)sender;   // Removed based on answer.  
- (void)windowWillClose:(NSNotification*)notification;  // Added based on answer.   
- (void)windowDidBecomeKey:(NSNotification*)notification;  // To set title when modal.  
@end  

//  TheDialogController.m  
//  TestModalDialog  

#import "TheDialogController.h"  

@implementation TheDialogController  

- (id)init  
{  
  self = [super initWithWindowNibName:@"TheDialog"];  

  userClickedOk= 0;  // Added based on answer.  
  // userClickedCloseOrOk= FALSE;  // Removed based on answer.  

  return self;  
}  

-(void)dealloc  
{  
  // Do member cleanup if needed.
  [super dealloc];  
}  

- (void)windowDidLoad  
{  
  [super windowDidLoad];  

  // Initialize as needed....  
  [[self window] center];  // Center the window.  
}  

// Does not show with runModalForWindow.  
- (IBAction)showWindow:(id)sender  
{  
  // Just playing with the window title....  
  ++timesShown;  
  NSString* newTitle= [NSString stringWithFormat:@"Shown %d Times", timesShown];  
  [[self window] setTitle:newTitle];  
  return [super showWindow:sender];  
}  

// This method no longer used for this solution based on the answer.  
//- (BOOL)windowShouldClose:(id)sender  
//{  
//  if(!userClickedCloseOrOk)  // The user did not click one of our buttons.  
//    [NSApp abortModal];  
//  else  
//    userClickedCloseOrOk= FALSE;  // Clear for next time.  
//  
//  return TRUE;  
//}  

// Added based on answer.  
- (void)windowWillClose:(NSNotification*)notification  
{  
  [NSApp stopModalWithCode:userClickedOk];  
  userClickedOk= 0;  // Reset for next time.  
}  

// Note - the title will update every time the window becomes key. To do the  
// update only once per modal session, a flag can be added. There might be a better  
// notification to catch.  
- (void)windowDidBecomeKey:(NSNotification*)notification  
{  
  ++timesShown;  
  NSString* newTitle= [NSString stringWithFormat:@"Shown %d Times", timesShown];  
  [[self window] setTitle:newTitle];  
}  

- (IBAction)closeDialog:(id)sender  
{  
  //userClickedCloseOrOk= TRUE;  // Removed based on answer.  
  //[NSApp abortModal];  // Removed based on answer.  
  //[[self window] performClose:self];  // Removed based on answer.  
  [[self window] close];  // Know we want to close - based on answer.  
}  

- (IBAction)okDialog:(id)sender  
{  
  userClickedOk= 1;  // Added based on answer.  
  //userClickedCloseOrOk= TRUE;  // Removed based on answer.  
  //[NSApp stopModal];  // Removed based on answer.  
  //[[self window] performClose:self];  // Removed based on answer.  
  [[self window] close];  // Know we want to close - based on answer.  
}    

@end  

我在模态方面遇到了问题 - 在我输入 userClickedCloseOrOk 并进行测试之前，如果用户点击关闭按钮(左上角的红点)，对话框将关闭但模态 session 仍在运行。

我意识到我可以直接将关闭按钮从对话框中移除，但是有了它，我所展示的是捕捉该场景的好方法，还是有更好的方法？或者，我是不是一开始就做错了什么，这给我带来了问题？

如有任何建议，我们将不胜感激。

注意 - 原始示例中的代码被注释掉并替换为基于答案的代码。还添加了一个新的通知处理程序。

Answer 1

在 okDialog: 和 closeDialog: 方法中调用 close 而不是 performClose: 以避免窗口调用windowShouldClose: 委托(delegate)方法。这样你就不需要 userClickedCloseOrOk。

此外，我认为您想调用 stopModalWithCode: 而不是 stopModal 因为在应用委托(delegate)中您似乎对结果感兴趣。你可以调用 stopModal 或 stopModalWithCode: 而不是 abortModal 因为当你调用它时你总是在运行循环中(中止是当你在模式运行循环之外，比如在另一个线程或定时器的运行循环中)。

在 windowShouldClose: 中，您正在执行操作 (abortModal)，此时您应该只回答“应该关闭此窗口”的问题。 windowWillClose: 委托(delegate)方法是您应该在需要时执行操作的地方。

工作表在只有一个窗口时很有用，它告诉用户在完成工作表中的任何内容之前不能使用它做任何事情。当您有多个窗口时，用户无法与之交互，直到他们完成模式窗口中的任何内容，或者存在涉及整个应用程序但与一个窗口的内容无关的错误时，应用程序模式窗口很有用。在他们的 HIG 中，Apple 建议尽可能避免使用应用程序模式窗口。