等待[NSAlert beginSheetModalForWindow:…];

我们创建了一个 category on NSAlert to run alerts synchronously ,就像应用程序模式对话框一样:

NSInteger result;

// Run the alert as a sheet on the main window
result = [alert runModalSheet];

// Run the alert as a sheet on some other window
result = [alert runModalSheetForWindow:window];

该代码可通过 GitHub ,并将当前版本发布在下面以确保完整性。

头文件 NSAlert+SynchronousSheet.h :

#import <Cocoa/Cocoa.h>


@interface NSAlert (SynchronousSheet)

-(NSInteger) runModalSheetForWindow:(NSWindow *)aWindow;
-(NSInteger) runModalSheet;

@end

NSAlert+SynchronousSheet.m :

#import "NSAlert+SynchronousSheet.h"


// Private methods -- use prefixes to avoid collisions with Apple's methods
@interface NSAlert ()
-(IBAction) BE_stopSynchronousSheet:(id)sender;   // hide sheet & stop modal
-(void) BE_beginSheetModalForWindow:(NSWindow *)aWindow;
@end


@implementation NSAlert (SynchronousSheet)

-(NSInteger) runModalSheetForWindow:(NSWindow *)aWindow {
    // Set ourselves as the target for button clicks
    for (NSButton *button in [self buttons]) {
        [button setTarget:self];
        [button setAction:@selector(BE_stopSynchronousSheet:)];
    }

    // Bring up the sheet and wait until stopSynchronousSheet is triggered by a button click
    [self performSelectorOnMainThread:@selector(BE_beginSheetModalForWindow:) withObject:aWindow waitUntilDone:YES];
    NSInteger modalCode = [NSApp runModalForWindow:[self window]];

    // This is called only after stopSynchronousSheet is called (that is,
    // one of the buttons is clicked)
    [NSApp performSelectorOnMainThread:@selector(endSheet:) withObject:[self window] waitUntilDone:YES];

    // Remove the sheet from the screen
    [[self window] performSelectorOnMainThread:@selector(orderOut:) withObject:self waitUntilDone:YES];

    return modalCode;
}

-(NSInteger) runModalSheet {
    return [self runModalSheetForWindow:[NSApp mainWindow]];
}


#pragma mark Private methods

-(IBAction) BE_stopSynchronousSheet:(id)sender {
    // See which of the buttons was clicked
    NSUInteger clickedButtonIndex = [[self buttons] indexOfObject:sender];

    // Be consistent with Apple's documentation (see NSAlert's addButtonWithTitle) so that
    // the fourth button is numbered NSAlertThirdButtonReturn + 1, and so on
    NSInteger modalCode = 0;
    if (clickedButtonIndex == NSAlertFirstButtonReturn)
        modalCode = NSAlertFirstButtonReturn;
    else if (clickedButtonIndex == NSAlertSecondButtonReturn)
        modalCode = NSAlertSecondButtonReturn;
    else if (clickedButtonIndex == NSAlertThirdButtonReturn)
        modalCode = NSAlertThirdButtonReturn;
    else
        modalCode = NSAlertThirdButtonReturn + (clickedButtonIndex - 2);

    [NSApp stopModalWithCode:modalCode];
}

-(void) BE_beginSheetModalForWindow:(NSWindow *)aWindow {
    [self beginSheetModalForWindow:aWindow modalDelegate:nil didEndSelector:nil contextInfo:nil];
}

@end

解决办法是打电话

[NSApp runModalForWindow:alert];

下面是一个NSAlert类别,它解决了这个问题(正如Philipp所建议的由Frederick提出并由Laurent P改进的解决方案:我使用一个代码块而不是委托,因此它再次被简化)。

@implementation NSAlert (Cat)

-(NSInteger) runModalSheetForWindow:(NSWindow *)aWindow
{
    [self beginSheetModalForWindow:aWindow completionHandler:^(NSModalResponse returnCode)
        { [NSApp stopModalWithCode:returnCode]; } ];
    NSInteger modalCode = [NSApp runModalForWindow:[self window]];
    return modalCode;
}

-(NSInteger) runModalSheet {
    return [self runModalSheetForWindow:[NSApp mainWindow]];
}

@end

为了防止有人来找这个(我找到了),我用以下方法解决了这个问题:

@interface AlertSync: NSObject {
    NSInteger returnCode;
}

- (id) initWithAlert: (NSAlert*) alert asSheetForWindow: (NSWindow*) window;
- (NSInteger) run;

@end

@implementation AlertSync
- (id) initWithAlert: (NSAlert*) alert asSheetForWindow: (NSWindow*) window {
    self = [super init];

    [alert beginSheetModalForWindow: window
           modalDelegate: self didEndSelector: @selector(alertDidEnd:returnCode:) contextInfo: NULL];

    return self;
}

- (NSInteger) run {
    [[NSApplication sharedApplication] run];
    return returnCode;
}

- (void) alertDidEnd: (NSAlert*) alert returnCode: (NSInteger) aReturnCode {
    returnCode = aReturnCode;
    [[NSApplication sharedApplication] stopModal];
}
@end

然后同步运行NSAlert非常简单:

AlertSync* sync = [[AlertSync alloc] initWithAlert: alert asSheetForWindow: window];
int returnCode = [sync run];
[sync release];

请注意,正如所讨论的,存在重新进入问题的可能性,因此在进行此操作时要小心。

然而,对于你需要的东西来说,这可能真的太复杂了。在这种情况下,我的建议是只使用不推荐的用法,但这实际上取决于您的用户需求。

extension NSAlert {

  /// Runs this alert as a sheet.
  /// - Parameter sheetWindow: Parent window for the sheet.
  func runSheetModal(for sheetWindow: NSWindow) -> NSApplication.ModalResponse {
    beginSheetModal(for: sheetWindow, completionHandler: NSApp.stopModal(withCode:))
    return NSApp.runModal(for: sheetWindow)
  }
}

创建全局类变量“NSInteger alertReturnStatus”

- (void)alertDidEndSheet:(NSWindow *)sheet returnCode:(NSInteger)returnCode contextInfo:(void *)contextInfo
{
    [[sheet window] orderOut:self];
    // make the returnCode publicly available after closing the sheet
    alertReturnStatus = returnCode;
}


- (BOOL)testSomething
{

    if(2 != 3) {

        // Init the return value
        alertReturnStatus = -1;

        NSAlert *alert = [[[NSAlert alloc] init] autorelease];
        [alert addButtonWithTitle:@"OK"];
        [alert addButtonWithTitle:@"Cancel"];
        [alert setMessageText:NSLocalizedString(@"Warning", @"warning")];
        [alert setInformativeText:@"Press OK for OK"];
        [alert setAlertStyle:NSWarningAlertStyle];
        [alert setShowsHelp:NO];
        [alert setShowsSuppressionButton:NO];

        [alert beginSheetModalForWindow:[self window] modalDelegate:self didEndSelector:@selector(alertDidEndSheet:returnCode:contextInfo:) contextInfo:nil];

        // wait for the sheet
        NSModalSession session = [NSApp beginModalSessionForWindow:[alert window]];
        for (;;) {
            // alertReturnStatus will be set in alertDidEndSheet:returnCode:contextInfo:
            if(alertReturnStatus != -1)
                break;

            // Execute code on DefaultRunLoop
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode 
                                     beforeDate:[NSDate distantFuture]];

            // Break the run loop if sheet was closed
            if ([NSApp runModalSession:session] != NSRunContinuesResponse 
                || ![[alert window] isVisible]) 
                break;

            // Execute code on DefaultRunLoop
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode 
                                     beforeDate:[NSDate distantFuture]];

        }
        [NSApp endModalSession:session];
        [NSApp endSheet:[alert window]];

        // Check the returnCode by using the global variable alertReturnStatus
        if(alertReturnStatus == NSAlertFirstButtonReturn) {
            return YES;
        }

        return NO;
    }
    return YES;
}

希望能有所帮助, --汉斯

这是上面Laurent等人的版本,已翻译成适用于Xcode 6.4的Swift 1.2(截至今天的最新工作版本),并在我的应用程序中进行了测试。感谢所有为这项工作做出贡献的人!苹果公司的标准文档没有给我任何关于如何进行这项工作的线索,至少在我能找到的任何地方都没有。

还有一个谜团留给我:为什么我必须在最后一个函数中使用双感叹号。NSApplication.mainWindow应该只是一个可选的NSWindow(NSWindow?),对吗?但是编译器给出了显示的错误,直到我使用第二个“!”为止。

extension NSAlert {
    func runModalSheetForWindow( aWindow: NSWindow ) -> Int {
        self.beginSheetModalForWindow(aWindow) { returnCode in
            NSApp.stopModalWithCode(returnCode)
        }
        let modalCode = NSApp.runModalForWindow(self.window as! NSWindow)
        return modalCode
    }

    func runModalSheet() -> Int {
        // Swift 1.2 gives the following error if only using one '!' below:
        // Value of optional type 'NSWindow?' not unwrapped; did you mean to use '!' or '?'?
        return runModalSheetForWindow(NSApp.mainWindow!!)
    }
}

与Windows不同,我不相信有一种方法可以阻止模态对话框。输入(例如,用户单击按钮)将在主线程上处理,因此无法阻止。

当一个对象出现故障时,停止处理树中的对象,记下哪个对象出现故障(假设有一个订单,您可以从您停止的地方继续),然后扔掉工作表。当用户撤销工作表时,请 didEndSelector: 方法从它离开的对象重新开始处理,或不开始处理,具体取决于 returnCode .

- (bool) windowShouldClose: (id) sender
 {// printf("windowShouldClose..........\n");
  NSAlert *alert=[[NSAlert alloc ]init];
  [alert setMessageText:@"save file before closing?"];
  [alert setInformativeText:@"voorkom verlies van laatste wijzigingen"];
  [alert addButtonWithTitle:@"save"];
  [alert addButtonWithTitle:@"Quit"];
  [alert addButtonWithTitle:@"cancel"];
  [alert beginSheetModalForWindow: _window modalDelegate: self
              didEndSelector: @selector(alertDidEnd: returnCode: contextInfo:)
                 contextInfo: nil];
  return false;
}

你可以用 dispatch_group_wait(group, DISPATCH_TIME_FOREVER); :

dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);

NSAlert *alert = [[NSAlert alloc] init];
[alert setMessageText:@"alertMessage"];
[alert addButtonWithTitle:@"Cancel"];
[alert addButtonWithTitle:@"Ok"];

dispatch_async(dispatch_get_main_queue(), ^{
    [alert beginSheetModalForWindow:progressController.window completionHandler:^(NSModalResponse returnCode) {
         if (returnCode == NSAlertSecondButtonReturn) {
             // do something when the user clicks Ok

         } else {
             // do something when the user clicks Cancel
         }

         dispatch_group_leave(group);
     }];
});

dispatch_group_wait(group, DISPATCH_TIME_FOREVER);

//you can continue your code here

希望有帮助。