NSOpenPanel模型窗口杀死主应用程序窗口

Question

我是Mac应用程序编程的新手。 我正在使用NSOpenPanel从系统中选择一个文件。一旦我选择了一个文件，然后按下取消/打开按钮，就会执行completionHandler块。

当OpenPanel窗口关闭时，我面临以下问题：

1. 即使mainAppWindow.visible的结果为1
，我的主应用程序窗口也会关闭
2. 另外，我没有收到主App窗口的窗口关闭委托方法。

请在下面找到我用来创建NSOpenPanel的代码段。

-(void)openFile
{
    //this gives you a copy of an open file dialogue
    NSOpenPanel*openPanel = [NSOpenPanel openPanel];

    //set the title of the dialogue window
    openPanel.title = @"Choose a .zip formate file";

    //shoud the user be able to resize the window?
    openPanel.showsResizeIndicator = NO;

    //should the user see hidden files (for user apps - usually no)
    openPanel.showsHiddenFiles = NO;

    //can the user select a directory?
    openPanel.canChooseDirectories = NO;

    //can the user create directories while using the dialogue?
    openPanel.canCreateDirectories = NO;

    //should the user be able to select multiple files?
    openPanel.allowsMultipleSelection = NO;

    //an array of file extensions to filter the file list
    openPanel.allowedFileTypes = @[@"zip"];

    [openPanel beginWithCompletionHandler:^(NSInteger result) {

        //if the result is NSOKButton
        //the user selected a file

            if (result==NSModalResponseOK) {

                //Do something
            }
            else if (result== NSModalResponseCancel)
            {
                //do something
            }
    }];  
}