objective-c - 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。它显示了一些NSView，NSWindow问题是我无法修改它的代码。原始模型层次结构如下所示：

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

我想改变层次结构如下：

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

如何使用？NSView_NSViewNSStackView

我目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NSWindow，运行此代码后仅显示“第二视图”标签：

Answer 1

[_window setContentView:st]调用removeFromSuperview旧的内容视图并removeFromSuperview释放视图。[firstView removeFromSuperview]并且[_window setContentView:st]都将释放firstView.

解决方案：替换[firstView removeFromSuperview]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];
}