如何将NSStackView注入视图层次结构？

Question

我有一个OSX应用程序用Objective写的。它在一个NSView中显示一些NSWindow，问题是我不能修改它的代码。原始模型层次结构如下所示：

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

我想按以下方式改变等级制度：

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

如何使用NSView同时显示原始NSView和相邻的附加NSView

我目前的方法或多或少是这样的(示例是简化的)：

- (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只显示“第二个视图”标签：

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Answer 1

[_window setContentView:st]在旧的内容视图上调用removeFromSuperview，removeFromSuperview释放该视图。[firstView removeFromSuperview]和[_window setContentView:st]都将发布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];
}