如何在Cocoa应用程序中实现消息框？

我已经在cocoa应用程序中实现了删除功能，现在我想在用户单击“删除”按钮时显示一个消息框。

看一下，它有一个同步方法：

正如Peter提到的，更好的选择是使用窗口上的警报，例如：

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

可通过以下方式添加按钮：

返回代码告诉您按下了哪个按钮：

- (void) alertDidEnd:(NSAlert *)a returnCode:(NSInteger)rc contextInfo:(void *)ci {
    switch(rc) {
        case NSAlertFirstButtonReturn:
            // "First" pressed
            break;
        case NSAlertSecondButtonReturn:
            // "Second" pressed
            break;
        // ...
    }
}

---

自从得到公认的答案以来，已经过了很长一段时间，事情发生了变化：

• 斯威夫特越来越受欢迎

• beginSheetModalForWindow（uxAE:modalDelegate:DiEndSelector:contextInfo:）

  已被弃用，我们应该改用

  beginSheetModalForWindow:completionHandler:

Swift中的最新代码示例：

func messageBox() {
    let alert = NSAlert()
    alert.messageText = "Do you want to save the changes you made in the document?"
    alert.informativeText = "Your changes will be lost if you don't save them."
    alert.addButtonWithTitle("Save")
    alert.addButtonWithTitle("Cancel")
    alert.addButtonWithTitle("Don't Save")
    alert.beginSheetModalForWindow(window, completionHandler: savingHandler)
}

func savingHandler(response: NSModalResponse) {
    switch(response) {
    case NSAlertFirstButtonReturn:
        println("Save")
    case NSAlertSecondButtonReturn:
        println("Cancel")
    case NSAlertThirdButtonReturn:
        println("Don't Save")
    default:
        break
    }
}

如果需要同步版本，请执行以下操作：

func messageBox() {
    let alert = NSAlert()
    alert.messageText = "Do you want to save the changes you made in the document?"
    alert.informativeText = "Your changes will be lost if you don't save them."
    alert.addButtonWithTitle("Save")
    alert.addButtonWithTitle("Cancel")
    alert.addButtonWithTitle("Don't Save")
    let result = alert.runModal()
    switch(result) {
    case NSAlertFirstButtonReturn:
        println("Save")
    case NSAlertSecondButtonReturn:
        println("Cancel")
    case NSAlertThirdButtonReturn:
        println("Don't Save")
    default:
        break
    }
}

---

更好的是，在包含“删除”按钮的窗口中，以工作表的形式开始警报。通过这种方式，用户可以继续使用应用程序中的任何其他窗口。哇，它工作得很好。但是如何在此警报中放置更多按钮以及如何获取这些按钮呢events@mik：使用。文档中还有一个可能会对您有所帮助的选项：[alert beginSheetModalForWindow:[NSApp mainWindow]completionHandler:^（NSModalResponse returnCode）{if（returnCode==NSAlertFirstButtonReturn）{}}；你救了我一天！

func messageBox() {
    let alert = NSAlert()
    alert.messageText = "Do you want to save the changes you made in the document?"
    alert.informativeText = "Your changes will be lost if you don't save them."
    alert.addButtonWithTitle("Save")
    alert.addButtonWithTitle("Cancel")
    alert.addButtonWithTitle("Don't Save")
    alert.beginSheetModalForWindow(window, completionHandler: savingHandler)
}

func savingHandler(response: NSModalResponse) {
    switch(response) {
    case NSAlertFirstButtonReturn:
        println("Save")
    case NSAlertSecondButtonReturn:
        println("Cancel")
    case NSAlertThirdButtonReturn:
        println("Don't Save")
    default:
        break
    }
}

func messageBox() {
    let alert = NSAlert()
    alert.messageText = "Do you want to save the changes you made in the document?"
    alert.informativeText = "Your changes will be lost if you don't save them."
    alert.addButtonWithTitle("Save")
    alert.addButtonWithTitle("Cancel")
    alert.addButtonWithTitle("Don't Save")
    let result = alert.runModal()
    switch(result) {
    case NSAlertFirstButtonReturn:
        println("Save")
    case NSAlertSecondButtonReturn:
        println("Cancel")
    case NSAlertThirdButtonReturn:
        println("Don't Save")
    default:
        break
    }
}