Macos NSView自动调整大小以适应contentview

当窗口调整大小时，如何使

customView.frame.size.height

始终等于

contentView.frame.size.height

，同时

customView.frame.size.width=20？
设置自定义视图的自动重新设置任务：

CustomView *customView = [[CustomView alloc] init];
customView.autoresizingMask = NSViewWidthSizable | NSViewHeightSizable;
[self.window.contentView addSubview:customView];

Swift版本，用于应用自动重新定位任务：

CustomView *customView = [[CustomView alloc] init];
customView.autoresizingMask = NSViewWidthSizable | NSViewHeightSizable;
[self.window.contentView addSubview:customView];


let customView = CustomView()
customView.autoresizingMask = [.width, .height]
self.window.contentView.addSubview(customView)