如何将NSStackView注入视图层次结构？

Question

我有一个用Objective-C编写的OSX应用程序。 它在NSView中显示一些NSWindow， 问题是我无法修改其代码。原始模型层次结构如下所示：

NSWindow
|---> original NSView
      |---> (...)

我想按如下方式更改层次结构：

NSWindow
|---> NSStackView
      |---> original NSView
      |     |---> (...)
      |---> some additional NSView (say NSTextField)

如何使用NSView并排显示原始的NSView和附加的NSStackView？

我当前的方法或多或少是这样的（示例已简化）：

- (void)createFirstView {
    NSTextField *label1 = [NSTextField labelWithString:@"First view."];
    [_window setContentView: label1];
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // I cannot modify this procedure:
    [self createFirstView];

    // I can modify that:
    NSTextField *label2 = [NSTextField labelWithString:@"Second view."];

    NSView *firstView = [_window contentView];
    [firstView removeFromSuperview];
    NSStackView *st = [NSStackView stackViewWithViews:@[firstView, label2]];
    [_window setContentView:st];
}

不幸的是，运行此代码后的NSWindow仅显示“第二视图”标签：

Answer 1

[_window setContentView:st]在旧内容视图上调用removeFromSuperview，然后removeFromSuperview释放该视图。 [firstView removeFromSuperview]和[_window setContentView:st]都将释放firstView。

解决方案：将[firstView removeFromSuperview]替换为[_window setContentView:nil]。

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // I cannot modify this procedure:
    [self createFirstView];

    // I can modify that:
    NSTextField *label2 = [NSTextField labelWithString:@"Second view."];

    NSView *firstView = [_window contentView];
    [_window setContentView:nil];
    NSStackView *st = [NSStackView stackViewWithViews:@[firstView, label2]];
    [_window setContentView:st];
}